JUKI MH-380 Instruction Manual page 56

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Troubles
4. Needle breakage 1 Needle is bent.
5. Puckering
Causes
2 The timing of the needle motion with
that of needle is not correct.
3 Position of the presser foot is wrong.
4 Motion of the needle guard is not ad-
equate.
5 The tension of needle thread is too
high.
6 Thickness of the needle is not suitable.
1 Thread tension is too high.
2 Timing of the looper thread take-up is
wrong.
3 Thread paths are not smooth.
4 Pressing force of the presser foot is too
much.
Corrective measures
™ Replace it with a straight needle.
Refer to "11. ATTACHING THE NEEDLE".
™ Adjust the timing.
Refer to "14. ADJUSTING THE FEED TIM-
ING".
™ Align the needle holes on the throat plate and
the presser foot with the center line of the
needle.
™ Check the position and timing of the motion of
the needle guard.
Refer to "18. MATCHING THE MOTION OF
THE NEEDLE GUARDS WITH THE LOOP
GUIDE".
™ Loosen the tension.
Refer to "8. THREAD TENSION".
™ Replace it with a suitable needle in accordance
with the quality and weight of the sewing ma-
terial.
Refer to "11. ATTACHING THE NEEDLE".
™ Reduce the thread tension, especially the
looper thread.
Refer to "8. THREAD TENSION".
™ Adjust it, if necessary.
Refer to "19. POSITIONING THE LOOPER
THREAD TAKE-UP".
™ Make them smooth.
™ Adjust it by loosening the presser spring regu-
lator.
Refer to "9. ADJUSTING THE PRESSER
FOOT".
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