39
No Condition Checking Point Cause of Trouble Troubleshooting
Insufficient crossing quantity of movable
and fixed blade
Take-up lever pulls out the upper
thread because the needle up and
down position is too high
Crossing of trimmer cam
notch mark and blade
Up-stop position of
needle
Trimming errors
6
Adjust the stroke of movable and fixed
blade
Adjust the up-stop position of
needle
7
Upper thread is
pulled out when
sewing
commences
Upper thread is
not sunk
Lower thread is
not sunk
4
5
Too tight upper thread tension Reduce tension of upper thread
Too loose lower thread tension Increase tension of lower thread
Too weak upper thread tension Increase tension of upper thread
Too strong lower thread tension Decrease tension of lower thread
Tension of fixed blade
Tension not aligned between movable and fixed blade
Adjust tension of movable and fixed blade
Edge of movable and fixed blades Abrasion in blade groove of movable and fixed blade
Replace movable and fixed blade
Direction of needle Wrong needle insertion Reinsert the needle correctly
Too strong upper thread tension Adjust tension of upper thread
Too thick a needle for thread
Check thickness of needle
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