40
Weak upper thread tension
Weak lower thread tension
Improper needle and hook timing
Relaxed crossing tension of the moving and
fixed blades
Scratch or abrasion on the moving and fixed
blades
Wrong trimmer cam location
Bad thread tightening
condition
Missing thread
trimming
6
7
Adjust the upper thread tension
Adjust the lower thread tension
Adjust the needle and hook timing
Adjust the fixed blade tension
Replace the moving and fixed blades
Readjust the location of the trimmer cam
No
Trouble
Cause
Corrective Action