1, machine needle bending, tight needle screw loose.Need to replace machine needle and tighten needle screw.
2. The clearance between shuttle and needle is too small.Adjust the clearance.
3, clamping plate pressure is too tight, surface line tension is too large, adjust the tension.
4. Pin hole, pin plate hole and machine needle are not aligned.
5. The frame shifting Angle is wrong, adjust the frame shifting Angle.
6, machine needle quality is not good, replace machine needle.
7. Hook position deviation, adjust hook.