SunStar HC Series User Manual page 61

Error Type
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)
Cause
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
Inspection & Repair Reference
Set it at 0.5-0.7mm for
smooth feeding of upper
thread