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Troubles Causes Checking Corrective measures
Needle thread is not caught.
Bobbin thread is not caught.
Both needle and bobbin
threads cannot be trimmed.
Tension of the bobbin
thread is too high.
Kinfe pressure of the
counter knife is too high.
Initial position of the moving
knife is placed excessively
in the front.
Thread is not cut sharply.
Stitch skipping at the last
stitch
Check the thread trimmer
cam timing.
Top end of the moving knife
has broken or been
scratched.
Stroke of the moving knife
is small.
Check the routing of bobbin
thread.
Top end of the moving knife
has broken or been
scratched.
Check the height of moving
knife.
The blades of moving knife
and counter knife have
been improperly adjusted.
Pressure of the counter
knife is too low.
Moving knife fails to work.
Adjust the tension of bobbin
thread.
Refer to “Adjusting the knife
pressure” on page 27.
Refer to “Thread trimmer cam
timing” on page 31.
Refer to Causes “Thread
cannot be trimmed” and
“Thread remains uncut after
thread trimming” on page 51.
Refer to “Needle-to-hook
timing” on page 9.
Refer to “Thread trimmer cam
timing” on page 31.
Replace the moving knife with
a new one.
Adjust the initial position of
moving knife.
Correctly thread bobbin thread.
Replace the moving knife with
a new one.
Adjust the height of moving
knife.
Refer to “Adjusting the knife
pressure” on page 27.
Refer to “Adjusting the knife
pressure” on page 27.
Adjust the synchronizer timing.
Replace the thread trimmer
solenoid.
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