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ENGLISH
Troubles Causes Corrective measures
2
An independent seam is skipped on the
looper thread.
Needle
Looper
This trouble is caused when the needle
failed ·to come down through a trian-
gular loop formed by the looper thread.
™
Verify the looper motion.
Verify the clearance between the looper and
the needle.
Refer to “19. NEEDLE-TO-LOOPER RELA-
TION”.
™
Check the timing of the looper thread take-up.
Refer to “23. POSITIONING THE LOOPER
THREAD TAKE-UP”.
™
Adjust the position of the thread spreader
hook.
Refer to “21. THREAD SPREADER”.
™
Increase the looper thread tension slightly.
Refer to “9. THREAD TENSION”.
™
Verify the thread is correctly passed through.
Refer to “7. THREADING THE MACHINE
HEAD” and “8. THREADING THE LOOP-
ERS”.
3
Seam is skipped on the needle thread
due to insuffi cient interlooping.
Needle
Looper
This trouble is caused when the needle
thread is inclined extremely to the left.
™
Verify the looper motion.
Verify the clearance between the looper and
the needle.
Refer to “19. NEEDLE-TO-LOOPER RELA-
TION”.
If it is caused in the use of a chemical
fi ber thread.
™
Reduce the sewing speed.
™
Apply silicon oil lubricant.
Refer to “11. HOW TO INSTALL THE SILI-
CON OIL LUBRICATING UNIT”.
™
Use a needle for chemical fi ber threads.
If it is caused in the use of a synthetic
fi ber thread.
™
Make the scooping amount of looper greater.
Refer to “19. NEEDLE-TO-LOOPER RELA-
TION”.
™
Reduce the sewing speed.
™
Apply silicon oil lubricant.
Refer to “11. HOW TO INSTALL THE SILI-
CON OIL LUBRICATING UNIT”.
3. Inadequate tight-
ness of stitches
1
Needle thread tension is too low.
™
Tighten the needle thread tension nut.
Refer to “9. THREAD TENSION”.
2
Looper thread tension is too high.
™
Loosen the looper thread tension nut.
Refer to “9. THREAD TENSION”.
3
Looper thread take-up does not supply
a suffi cient length of thread.
™
Change the threading order in the looper thread
guide.
Refer to “23. POSITIONING THE LOOPER
THREAD TAKE-UP”.
4
Thread is too thick for the needle size.
™
Try to use a different needle.
Refer to “6. ATTACHING THE NEEDLE”.
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