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Thread threading is not smooth due
to incorrect polishing in stitch tongue.
Stitch skip in top covering stitch due
to incorrect adjustment
Stitch skip due to incorrect adjustment
Drawing-in amount of top covering
thread is too much or too little.
Needle thread tension is too weak.
Incorrect threading
1st thread tension is too weak.
Thread threading is not smooth due
to incorrect shape of stitch tongue.
Worn out needle point, needle bend,
wrong needle
Flaw on surface in feed dog
Remaining thread is too short by
double cutting.
Clamping force is too weak.
Pulling-in amount of thread is too little
at time of thread trimming.
Clamping force is too weak.
Needle is entangled with thread by
incorrect direction of air blow outlet.
Falling speed of presser is too slow in
automatic lifter.
Replace when polished or its shape is changed too
much.
Refer to standard adjustment.
Refer to standard adjustment.
Refer to standard adjustment.
Increase tension.
Refer to threading diagram.
Increase tension.
Replace when its shape is modified or changed too
much.
Replace needle with new one, Use UY121GJS
CS100, UY128GBS FS300.
Modify or replace.
Refer to standard adjustment.
Increase clamping force.
Increase pulling-in amount.
Increase clamping force.
Correct direction so that remaining thread flows to
presser bar side.
Increase falling speed. (to get rid of shaky
movement etc.)
Troubles(1)
Troubles(2)
Cause (1)
Cause (2)
Corrective measures
From the previous page
To the next page
Defective chain-off thread
(with top covering stitch)
Stitch skip & stitch missing at
start of sewing after thread
trimming (thread trimmer
sewing machine, bottom
covering stitch)
Throat plate
Spreader adjustment
Looper adjustment
Top covering thread take-up
Needle thread tension
Threading
Top covering thread tension
Stitch tongue of presser foot
Needle
Feed dog
Double cutting
Looper thread clamp
Pulling-in of thread
Mechanical wiper
Pneumatic wiper
Presser foot
From
the
library
of:
Diamond
Needle
Corp