48
No
6
7
Problems Causes
Weak tension of the upper thread
Weak tension of the lower thread
Troubleshooting
Adjust the tension of the upper thread
Errors in thread tension
Incorrect timing of the needle and the shuttle
Loose crossing tension between the
movable and fixed blades
Adjust the timing of the needle and the shuttle
Adjust the tension of the fixed blade
Errors in trimming
Abrasion of blade edges of the movable and fixed blades
Replace the movable and fixed blades
Adjust the tension of the lower thread
Wrong position of the trimmer cam
Adjust the position of the trimmer cam