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Square Baler Knotter Missing Knots on One Side? Troubleshooting Guide
Introduction
You look in the rearview mirror and see a frustrating sight: perfectly formed bales, except the twine on the left (or right) side is flapping loose.
When a square baler misses knots on one side only, the good news is that your main timing is likely fine. The bad news is that a specific component on that knotter stack has failed or worn out.
Whether you are running an AGCO MF2270, a Claas Quadrant, or a New Holland, the physics of the knotter are similar. In this guide, Agmishop’s technical team helps you diagnose why one side is failing while the other works perfectly.
Step 1: Analyze the “Miss-Tie” (Read the Twine)
Before you touch a wrench, pick up the broken twine. The shape of the failure tells you exactly which part is broken.
Scenario A: A Simple Knot at the End (Loop)
- The Look: There is a knot in one end of the twine, but the other end pulled out.
- The Diagnosis: The knot was formed, but it failed to tighten or stripped off poorly.
- Likely Culprit: The Billhook or Stripper Arm.
Scenario B: No Knot (Straight Twine)
- The Look: The twine is straight with a frayed end, or it looks like it was cut.
- The Diagnosis: The twine slipped out of the holder before the knot could be tied.
- Likely Culprit: The Twine Disc (Holder) or Twine Tension.
Step 2: Check Twine Tension (The Easiest Fix)
Often, the side that is missing knots simply has incorrect tension compared to the working side.
- Box Tension: Check the twine box. Is the twine caught on a spool? Is it feeding smoothly?
- Tensioner Plates: Check the spring-loaded plates near the needles. If the tension is too loose, the billhook cannot grab the twine. If it is too tight, the twine snaps.
Step 3: Inspect the Billhook (The Usual Suspect)
If you have a knot that hangs on the beak or pulls apart (Scenario A), the problem is almost always the billhook on that specific side.
The Fingernail Test
Open the billhook jaw (tongue). Run your fingernail along the inside surface of the tongue and the roller.
- What to look for: A groove or a sharp burr worn into the metal.
- The Problem: If there is a groove, the twine gets “locked” in it. The stripper arm cannot wipe the knot off, so the twine snaps as the bale pushes back.
- The Solution: Do not try to file it down. Once the case-hardening is gone, it will fail again in 50 bales. Replace the billhook.
Step 4: The Twine Disc & Holder
If the twine is slipping out before the knot forms (Scenario B), inspect the twine disc on the failing side.
- Timing: Is the notch in the disc advancing far enough to grab the twine from the needle? Compare it visually to the working side.
- Wear: Look at the cleaner plate and the disc notches. If the edges are rounded or razor-sharp, they will cut the twine prematurely.
- Leaf Spring: Check the heavy leaf spring that holds the twine in the disc. If it is cracked or weak, it lets go of the twine too early.
Step 5: The Wiper (Stripper) Arm
The wiper arm has to physically push the knot off the billhook.
- Rub Test: The wiper should gently rub against the back of the billhook as it passes. If there is a gap, it will miss the knot.
- Bend it back: Sometimes, you can gently bend the wiper arm malleable iron to restore contact. However, if the knife on the wiper arm is dull, replace the blade.
Why One Side Fails First?
Why does the left side break while the right side is fine?
- Uneven Feeding: If you consistently drive so the windrow feeds into one side of the pickup, that side’s knotter works harder (handling denser flakes) and wears out faster.
- Debris: One side might be accumulating more chaff, blocking the mechanism.
Conclusion: Restore Your Reliability
A “one-sided” knotter problem is a clear sign of localized component wear. Stop fighting with adjustments. If your billhook has a groove or your twine disc is rounded, replacement is the only permanent fix.
At Agmishop, we stock precision-engineered knotter parts for AGCO, Claas, New Holland, and John Deere balers.