Thread pull-outs can be frustrating, but most causes are simple to diagnose and fix. Below is a step-by-step guide to help you identify and resolve the issue.
The most common reason for thread pull-outs is improper tension. Inspect the back of your design. A correct stitch should show a balanced ratio of top and bobbin thread. If you see very little bobbin thread, the bobbin may be too tight or the top thread too loose. To test this, perform the bobbin drop test. The bobbin should drop 1 to 1.5 inches. If the bobbin checks out, tighten the top tension. Always turn both the small and large tension knobs together to keep balance.
Next, inspect the picker. The picker is the forked component beside the bobbin area. Its role is to align the bobbin thread after a trim so the first few stitches tie in correctly. Push the picker in fully and use the thin black support bracket above it as a straight edge. If the picker arm is bent or twisted, carefully bend it back. Make sure the picker arm does not touch the black screw on the left side of the support bracket. If it does, loosen the two small Phillips screws on the picker and lower the arm slightly. The bobbin pigtail should sit in the centre of the picker’s two prongs. If not, adjust the picker position and re-tighten the screws.
If the picker is fine, check the AUTO BACKTACK setting. This function reinforces stitches after trims, reducing thread pull-outs. On LCD control panels with design display, press SETTING, scroll to EMB PARAMETERS, and set AUTO BACKTACK to ALL. On LED control panels with text-only display, press MACHINE, select EMBROIDERY FUNCTION and press SET, then locate AUTO BACKTACK and set it to ALL (usually option 3 or “A”).
If thread still pulls out, you may need to adjust inching mode. Inching stitches are the slow stitches at the start of sewing or just after a trim that ensure proper tie-in. On LCD panels, press SETTING, then M/C PARAMETERS, then SET. Set AFTER TRIM INCHING STITCH to 4. On the next screen, set INCHING STITCH to 3. On the following screen, set PICKER OFF TIMING to 40. Increasing these values leaves a longer thread tail, which helps connectivity after trims. If thread tails become too long and drag across the fabric, reduce the picker off timing slightly.
Finally, test the picker to make sure it is operating correctly. On LCD panels, press TOOLS, then MACHINE, then SET. Select MACHINE TEST, press SET, then choose PICKER TEST and press SET again. Press SET repeatedly and observe if the picker moves smoothly without sticking. On LED panels, press M-SETTING, then MACHINE TEST. Press SET, then START, and run several tests to confirm smooth movement. If the picker does not fire at all, the picker solenoid may be broken and will need replacement.
In summary, start with thread tension by using the bobbin drop test and adjusting top tension. Check the picker for straightness, clearance and pigtail position. Verify AUTO BACKTACK is set to ALL. Adjust inching stitches and picker timing if needed. Run the picker test to confirm smooth operation.