What is the reason why the lock core of mattress edger is loose and winding old?

1. The tension of the bobbin thread is too large and too small, which causes the bobbin thread to break loose, thus being pulled into the crochet and gear and winding the bobbin thread.

2. The bottom thread is wound around the crochet needle, blade and other parts, which leads to the bottom thread not passing smoothly and the winding is broken.

3. The sewing technology is incorrect, the sewing speed and tension are unbalanced, and the bottom needle cannot smoothly pass through the multi-layer cloth, thus being entangled and stuck.