It is possible that the leather of the sewing machine is broken, because the tightness of the upper thread is different, which makes the cloth unable to move forward. Because the bottom line of the fabric is too tight, wrinkles or broken skin are formed. At this time, it is necessary to replace the needle or increase the presser foot pressure.

Damaged leather can be repaired by hand sewing or sewing machine. You can remove scratches with a marker or shoe polish.