Scope and disclosure: XES manufactures bale net wrap, so we have an obvious commercial interest in twine's shortcomings. We have tried to be straight about that below — including citing Extension research that names net wrap's disadvantages. We are not a baler manufacturer or your dealer, and this is not a service manual. Mechanisms, adjustments, and timing marks differ by make, model, and serial range; your operator's and technical manuals govern. Brand and model names are used only to identify equipment.
Quick answer: Round baler twine problems sort into four symptoms, and each points somewhere different. Arms don't move at all — start at the drive, not the arms: a hydraulic system low on oil or full of air after a filter change, a failed motor or actuator, a blown fuse, or a monitor that lost power or ground. Arms sweep but the bale comes out wrapped on only part of its width — usually mechanical drag: hay packed around the arm pivots, a worn twine tensioner or guide with a groove worn into it, or a bent rod stopping arm travel — and very often a thin windrow center, because twine cannot hold what isn't there. The tie leaves a tail hanging — a cut-position problem, fixed by tucking: bringing the arm back in from the edge before the knife cuts, and by running the strings closer together. Arms bind or hit something — check spacers, plane, and timing marks; both twine tubes must sit in the same plane or the crossover linkage fights itself. Before any of that: grease the arm pivots. Seized pivot pins and dry bushings on a neglected machine cause more twine-arm faults than any electrical part.
1. How the twine system works — and the three different drives
The principle is the same on every round baler. When the bale reaches size, the twine feeds into the chamber, the rotating bale grabs it, and a twine arm (or a pair of them) sweeps across the width of the bale while it spins. That sweep lays twine in a spiral from one end to the other and usually back again. At the end, a knife cuts the twine and the arm returns to its home position ready for the next bale.
The part that trips people up is that "twine arm" describes a job, not a mechanism. The drive moving that arm is one of at least three different things depending on your machine:
- Hydraulic drive with its own small pump, reservoir, filter, and valve — common on older machines. This is why "check the twine pump oil level" is a real diagnostic step, and why a filter change can leave you with arms that will not move until the air is bled out.
- Electric motor drive — a motor turning the arm mechanism through gearing.
- Linear actuator drive — an electric ram that extends and retracts to sweep the arm.
Two balers from the same manufacturer, one model number apart, can use different drives. That matters enormously when you go looking for advice: a fix for a motor-driven machine is irrelevant on an actuator-driven one, and vice versa. Before you accept any diagnosis, confirm which drive your machine has.
One more piece of terminology worth clearing up, because it sends people chasing the wrong part: on some hydraulic systems what operators describe as "the piston" is actually a valve spool. Knowing it is a spool rather than a piston changes both the failure mode you should suspect and the part you order.
2. Match the symptom to the fault
Work this table before you take anything apart. The most common expensive mistake is ordering an actuator or motor for a machine whose real problem was a dry pivot pin or a thin windrow.
| What you observe | Check first | Then check |
|---|---|---|
| Arms make no attempt to move; no noise from the drive | Fuse, monitor power and ground, system voltage | Motor or actuator itself; hydraulic oil level |
| Drive runs or strains but arms move slowly, partway, or not at all | Mechanical bind — pivot pins, bushings, hay packed in the mechanism | Air in a hydraulic drive; missing or broken springs |
| Arms sweep fully but twine only covers part of the bale | Windrow shape — is the center of the bale full? | Worn tensioner or guide with a groove worn in it |
| Twine wraps but leaves a tail hanging off the end | Cut position — arm is at the outside edge when the knife fires | Tuck setting; string spacing; knife sharpness |
| Arm contacts the knife, striker plate, or frame | Spacers and arm plane — both tubes in the same plane? | Gear timing marks; home position |
| Twine breaks repeatedly at the same place | A worn part with a sharp groove in the twine path | Tension set too tight; wrong twine spec for the machine |
| Everything cycles but the monitor reports a fault | Sensor position and wiring, not the twine system | Monitor power source and system voltage reading |
If your fault is really a monitor or sensor issue rather than a mechanical one, that is a separate diagnostic path — see round baler monitor troubleshooting.
3. Symptom 1: the arms won't move at all
Split this immediately into "the drive isn't trying" versus "the drive is trying and something is stopping it." You can usually hear the difference.
If the drive isn't trying
Go electrical and hydraulic before mechanical:
- Fuses and power. Check the circuit feeding the twine function.
- Monitor power and ground. Voltage drop through a marginal connection can leave a monitor apparently alive but unable to command an output. Some monitors will display system voltage on a diagnostic channel — use it, because a reading well below battery voltage is a finding. Wiring the monitor directly to a clean power source is a common field diagnostic.
- Hydraulic oil level, on machines with a twine pump. Check it at the specified full mark, not "there's some in there."
- Air after a filter change. This one catches people every season. On a hydraulic twine drive, changing the filter dry introduces an air pocket. Filling the new filter with oil before installing it and then bleeding the system per the manual is often the whole fix — and skipping it means arms that will not move on a machine where nothing is actually broken.
If the drive is trying but the arms won't go
Now it is mechanical, and the answer is usually boring:
- Seized pivot pins and dry bushings. The arms rotate on pins that need grease. On machines with a neglected greasing history — auction and estate-sale balers especially — those pins rust into their bushings and the drive simply cannot overcome it. Free them, clean them, grease them, and confirm the arm swings by hand through its full range with the drive disconnected.
- Missing or broken springs. Some mechanisms rely on a specific number of springs. Count them against the parts diagram; a mechanism running one spring short behaves erratically rather than failing outright.
- Hay packed into the mechanism. Especially in leafy or damp crop, chaff builds into the arm pivots and the twine box until nothing moves freely.
If your twine drive is hydraulic, treat it with the same respect as any other hydraulic circuit on the machine. The Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice notes that agricultural hydraulic systems commonly run above 2,000 psi — and warns never to locate a leak by hand, to relieve pressure before opening any line, and to treat a fluid injection injury as an emergency requiring immediate medical care.
4. Symptom 2: the bale comes out half-wrapped
This is the most-reported twine complaint, and the most misdiagnosed — because the obvious conclusion ("the arm isn't traveling far enough") is often wrong.
Check the bale before you check the baler. If the center of the bale is soft or under-filled, twine laid across it has nothing to bite into and the wrap looks sparse or absent through the middle. That is a windrow problem, not a twine problem. It shows up constantly where a V-rake leaves a thin center in the windrow, and it disappears when the operator changes raking or weaves to fill the middle. No amount of twine-arm adjustment fixes a bale that is hollow in the middle.
Once you have ruled that out, work the mechanical causes in order:
- Hay and chaff buildup on the arms and pivots slowing or shortening travel. Clean it out and watch a full cycle.
- A worn twine tensioner or guide. Twine running over the same spot for thousands of bales cuts a groove into it. That groove grabs, drags, and changes how freely twine pays out mid-sweep. Run a fingernail over every surface in the twine path — anything with a groove is suspect and cheap to replace.
- A bent rod or component blocking travel. On some machines a hay compression or hold-down rod sits close to the arm path; if it gets bent, the arm stops short of its full sweep every single cycle. Compare against a parts diagram or the other side of the machine.
- Twine spacing set too wide for the crop, leaving visible gaps that read as "half-wrapped" even when the arm is traveling correctly.
A related failure worth naming: if the twine ties only at the ends and the bale sags in transport, the bale itself may be too soft. Density and binding are separate systems that get blamed for each other — if the bale is genuinely soft, see round baler density system troubleshooting and round bales not holding shape.
5. Symptom 3: the tie leaves a tail
A tail is the loose end left hanging after the knife cuts. It looks untidy, it snags in handling, and it ends up on the ground and in the feeding area — where it stays for years.
The cause is geometric. If the arm is sitting at the extreme outside edge of the bale when the knife fires, the cut end has nothing on top of it and simply hangs. The fix is a tuck: bring the arm back in toward the center of the bale after the end wraps are laid, let the rotating bale trap the twine under the following wrap, then move back out and cut. Several manufacturers implement exactly this in the machine's programming — the arm moves in from the edge, pauses while the bale takes up the slack, and returns to cut. If your machine has an adjustable tuck function, this is the first setting to work on.
Two supporting adjustments:
- Bring the strings closer together at the ends. Tighter spacing at the shoulders gives the tail more to be trapped under.
- Check the knife. A dull or misaligned knife tears rather than cuts, which leaves a frayed, longer end regardless of where the arm is.
Be honest with your expectations here: some operators run the tuck function and still get occasional tails, particularly in slick crop. Reducing tails is realistic; eliminating them entirely on every machine is not.
However you finish the tie, pick the tails up. Loose plastic twine ends accumulate in feeding areas and pastures for years, and they are exactly the material that gets ingested with feed. See the livestock note in section 9.
6. Symptom 4: the arms bind, rub, or hit something
Binding usually means one of three things: the arms are out of plane, out of time, or out of home position.
Plane. On twin-arm machines, both twine tubes must sit in the same plane. If one is shimmed differently from the other, the crossover linkage that ties them together fights itself through the sweep and something binds or contacts. This is where spacer count and placement matter, and where a lot of confusion comes from: manuals specify spacers as "left" or "right," and left is normally defined from the operator's seat looking forward — but service instructions are sometimes written from the perspective of standing behind the baler looking toward the tractor, which reverses it. If a spacer instruction gives you a result that obviously binds, you may have the sides swapped. Confirm the reference direction before you shim.
Time. Many arm drives use gears with timing marks. If the mechanism was apart and reassembled a tooth off, the arm's sweep is offset from the machine's cycle and it can travel into something. Find the marks in your technical manual and verify them — do not eyeball it.
Home position. The arm should park in a defined rest position. On some machines that is described relative to a specific fixed feature, such as sitting behind a particular bent rod. An arm that parks in the wrong place starts its sweep in the wrong place.
Finally, on the cut end of the cycle, the twine tube should pass cleanly and centered between the knife and its striker plate. If it is off-center there, you will see intermittent cut failures and contact wear on the tube.
7. Brand-specific notes
These are patterns commonly reported by operators, offered to help you search the right part of your manual — not as substitutes for it. Always verify against your model and serial range.
| Machine family | What operators commonly report |
|---|---|
| John Deere 530 / 535 | Hydraulic twine drive with its own pump, reservoir, and filter. Check oil at the full mark. Gear timing marks must line up. Home position is defined relative to a specific bent rod. The mechanism relies on a full set of springs — count them. Fill the filter with oil and bleed air after a change. What's often called "the piston" is a valve spool. |
| John Deere 567 and similar | Half-wrapped bales dominate. Order of investigation: windrow center → hay packed on arms → grooved tensioner or guide → bent hold-down rod limiting travel → monitor power and system voltage. Monitors on these machines report system voltage on a diagnostic channel; use it before condemning a component. |
| New Holland 650 and relatives | Twine tube spacer placement is the classic gotcha — a heavy spacer belongs on one specific arm only, and instructions may be written from behind the machine, reversing "left." Both tubes must sit in the same plane or the crossover linkage binds. The tube should center between knife and striker plate. |
| New Holland BR7050 vs BR7080 / BR7090 | Different drives within the same family: the smaller machine uses a motor while the larger ones use a linear actuator. Diagnostics do not transfer between them. Confirm which you have before following any advice. |
| Vermeer | Tails at the tie are the recurring complaint. The remedy is the tuck — program the arm back toward center after the end wraps, then out to cut — combined with closer string spacing. Results vary by machine; some operators report the tuck helping a lot and others little. |
Note the pattern across all five rows: only one of these is really an electrical-part failure. The rest are grease, geometry, adjustment, or crop presentation.
8. The maintenance that prevents most of this
A short pre-season routine removes most twine-arm faults before they cost you a field.
- Grease every arm pivot and zerk on the twine mechanism per the manual. This is the single highest-value item on the list.
- Swing each arm by hand through its full range with the drive disconnected. It should move freely with no catch and no contact.
- Run a fingernail along the whole twine path — tubes, guides, tensioners, eyelets. Replace anything with a groove worn into it.
- Blow out packed hay and chaff from the arm pivots and twine box.
- Check hydraulic oil level and change the filter properly on machines with a twine pump — fill the filter with oil, then bleed.
- Verify the knife is sharp and correctly positioned relative to the striker plate.
- Confirm timing marks if the mechanism has ever been apart.
- Count the springs against the parts diagram.
- Match your twine to the machine's spec. Twine that is wrong for your baler causes tension and breakage problems that look like mechanical faults — see our baler twine buying guide.
- Check the rest of the driveline while you're there — chains and bearings and belts are on their own schedules.
9. Should you switch to net wrap? An honest comparison
We sell net wrap, so read this section with that in mind — which is exactly why we are citing Extension research rather than our own marketing, including the parts that don't favor us.
South Dakota State University Extension lays out the trade-off with numbers:
| Factor | Twine | Net wrap |
|---|---|---|
| Turns to bind a bale | 20–30 | 2–3 |
| Throughput (University of Wisconsin–Madison, Shinners et al. 2002) | Baseline | 32% more bales per hour |
| Outdoor storage dry-matter loss (Shinners et al. 2002) | 11.3% | 7.3% |
| Binding cost per bale | Lower | Higher |
| Removal in snow and hard freeze | Easier | Can be difficult |
| Rumen degradability | Not degradable (plastic or "biodegradable" plastic) | Not degradable |
Three things follow from that table, and we would rather you hear them from us than find them out later.
The time saving is real but smaller than it sounds. "20–30 turns versus 2–3" makes net wrap sound like it eliminates the wrap cycle. In practice the tie is only part of the stop, and experienced operators who own both a twine baler and a net baler often describe the per-bale difference in seconds rather than tens of seconds. SDSU makes the same point from the other end: time saved at harvest can be offset by time spent removing wrap during winter feeding. If your operation's constraint is winter labor rather than harvest hours, net wrap's advantage shrinks.
Twine is cheaper per bale, and for some operations that settles it. If bales are fed on your own place within a few months, stored inside or under cover, and your baler's twine system works, the storage-loss advantage has less to recover. Livestock do not care how a bale is tied.
Neither binding is digestible, so both have to come off. SDSU cites an NDSU study (Klein and Dahlen, 2014) in which sisal, biodegradable plastic twine, and three types of net wrap were incubated in the rumen for 14 days — all the net wrap and the biodegradable plastic twine remained intact and undegraded. A Montana State trial feeding ground forage with binding over seven months found a large portion retained in the digestive tract. University of Nebraska–Lincoln Extension reaches the same conclusion. Remove it — ours included. We cover this at length in cattle eating net wrap and how to remove net wrap safely.
Where net wrap genuinely wins is outdoor storage and volume. If your bales sit outside through a season, the 7.3% versus 11.3% dry-matter difference compounds across every bale you made. University of Missouri Extension reinforces the mechanism: bales that shed water and hold their shape spoil less from the bottom. And if your twine system is chronically down mid-season, the cost comparison changes shape — a fault that stops the baler in a weather window is not a per-bale cost.
If you decide to make the change, many twine balers accept a factory or aftermarket net kit: see adding net wrap to a twine baler, the full net wrap vs twine comparison, and XES Extreme net wrap when you are ready to buy.
10. Frequently asked questions
Why won't my round baler twine arms move?
Listen first: if the drive makes no sound, check fuses, monitor power and ground, system voltage, and hydraulic oil level. If the drive strains but the arms don't travel, it is mechanical — seized pivot pins, dry bushings, packed hay, or missing springs. On hydraulic drives, air introduced during a filter change is a very common cause.
Why is my round baler only wrapping half the bale with twine?
Check the bale before the baler. A thin windrow center produces a soft middle that twine cannot grip, which reads as a half-wrapped bale. If the bale is full, look for hay packed on the arms, a twine guide or tensioner with a groove worn into it, or a bent rod stopping the arm short of full travel.
How do I stop my round baler leaving twine tails?
Use the tuck. Bring the arm back in from the outside edge after the end wraps so the rotating bale traps the twine under the following wrap, then move out and cut. Running the strings closer together at the ends helps, and a dull knife makes tails worse regardless of arm position.
What are twine arm timing marks and why do they matter?
Many twine arm drives use gears with alignment marks that set where the arm sits in the machine's cycle. Reassembling a tooth off offsets the entire sweep, which can make the arm travel into the knife, striker plate, or frame. If the mechanism has ever been apart, verify the marks against your technical manual.
Is net wrap actually faster than twine?
Yes, but less dramatically than turn counts suggest. SDSU Extension cites University of Wisconsin–Madison research finding 32% more bales per hour with net wrap. Operators who run both often describe the per-bale difference in seconds, and SDSU notes harvest time saved can be offset by slower wrap removal in winter feeding.
Does twine or net wrap store hay better outdoors?
Net wrap. SDSU Extension cites outdoor storage dry-matter losses of 7.3% for net wrap versus 11.3% for twine (Shinners et al., 2002). Net wrap sheds water better and helps bales hold shape, reducing bottom spoilage. Indoors or under cover, the gap narrows considerably.
Do I have to remove twine before feeding?
Yes — and net wrap too. NDSU research found sisal, biodegradable plastic twine, and net wrap all remained intact after 14 days of rumen incubation, and a Montana State trial found a large portion retained in the digestive tract after seven months. Remove all binding before feeding or grinding.
The bottom line
Twine-arm problems feel electrical and are usually not. Sort by symptom — nothing moves, partial wrap, tails, or binding — and the fault points itself out. Confirm which drive your machine uses before taking anyone's advice, check the windrow before condemning the mechanism, and grease the pivots before ordering a part. If your twine system keeps costing you weather windows, the net-wrap comparison is worth running honestly on your own numbers: net wrap earns its cost through outdoor storage and throughput, twine wins on price per bale, and either way the binding has to come off before it reaches an animal.
Featured photo: John Deere 7420 and 567 baler by Bill Burris, licensed under CC BY-SA 2.0, via Wikimedia Commons. XES Netting is not affiliated with, endorsed by, or sponsored by any baler manufacturer; brand and model names are used only to identify equipment.
