12-6
Error Type Cause
Dent on thread path on
hook and bobbin case
Narrow space between
hook holder and groove
for hook holder (on hook)
Insufficient oil in hook
Poor timing of needle and
hook
Incorrect lower dead stop
Dent on thread path
Fabric moves on the
frame
Inadequate height of
presser foot
(does not press the work
material)
Inspection & Repair
Remove dent or change the
case
Adjust space
Oil the raceway of hook
Adjust timing
Adjust the lower dead stop
Check:
•Thread path in presser foot
•Around needle hole on
needle plate
•Thread guide on the head
•Thread path in tension
adjuster
Fix the material firmly
Adjust height
Set it at 0.5-0.7mm for
smooth feeding of upper
thread
See 5-13)-4)
See 11-8)
See 11-7)
Reference
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