1. The first needle is broken, and the broken head is cut.

       Analysis: The needle is reversed or the needle is not filled, causing the needle to be too low. The sewing material is hard, the needle is too thin or the presser foot pressure is too large.

       Solution: Check that the needle is installed and the needle bar connection shaft screw is loose. Replace the needle or adjust the presser foot pressure.

       2. The suture is curled at both ends of the broken end and has a short whisker.

       Analysis: The tension is too tight or the stitching is mixed during sewing. The suture is squeezed into the shuttle guide slot. The suture is sturdy and easy to knot, the quality is poor, and there are burrs on the line.

       Treatment method: change the pressure of the clamping piece and check the line to eliminate the mixing. Check the wear of the shuttle and replace the shuttle if necessary. Sand the line and replace the stitch.

       3. The lower part of the sewing material is heavy, and the stitch length cannot be formed, and the broken line is ponytail-shaped.

       Analysis: The feed dog is too low, and the sewing material stops and the assembly line is too much broken. The cloth feed and the line step are not matched. The presser foot and the needle are loose, which hinders the sewing material from running.

       Treatment: Raise the feed dog, adjust the feed cam positioning angle, tighten the presser foot and the needle screw.