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WARNING :
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine.
Trouble
Cause (1)
Cause (2)
Checking order and adjusting procedure
6. Lower looper stitches are
skipped.
The upper looper does not
catch the lower looper thread.
(Stitch skipping at time of
crossing of upper and lower
loopers)
Right
side
Wrong
side
6-1)
Threading
1-A)
The thread has been entangled with a
thread guide. Threading has not been
done correctly.
Refer to the threading diagram.
6-2)
Upper looper
2-A)
The blade point has a bad shape, and
fails to catch the loops.
Replace the upper looper with badly deformed
blade point.
6-3)
Lower looper
3-A)
The clearance between the needle and
the back of lower looper are not correct.
Replace the lower looper with badly deformed
blade point.
6-4)
Adjustment of the
loopers
4-A)
The returning amount of the lower loop-
er, height of the upper looper, or clear-
ance produced at time of crossing of the
upper and lower loopers is not correct.
Refer to the pertinent Standard Adjustment.
6-5)
Thread amount
5-A)
Too much lower looper thread is fed,
giving slack of thread.
Slightly lower the looper thread take-up (left) to
decrease the amount of thread.
Slightly raise the looper thread take-up (right) to
decrease the amount of thread. Lower the lower
looper thread guide and shorten the lower looper
thread take-up to decrease the amount of thread.
7. Upper looer thread stitches
are skipped.
The needle does not take the
upper looper thread.
Lower looper
thread
Needle
Upper looper
Right
side
Wrong
side
7-1)
Threading
1-A)
The thread has been entangled with a
thread guide. Threading has not been
done correctly.
Refer to the threading diagram.
7-2)
Needle height
2-A)
The needle, if positioned too high or low,
may fail to catch the upper looper thread.
Refer to the pertinent Standard Adjustment.
7-3)
Needle
3-A)
The needle is bent or crushed, in its
point.
Replace the needle. At this time, be sure to elim-
inate the cause for such needle bend or needle
point crush.
7-4)
Adjustment of the
upper looper
4-A)
The height of the blade point is not cor-
rect, making the upper looper unable to
properly pass the thread to the needle.
The clearance between the needle and
the back of the upper looper is not cor-
rect.
Refer to the pertinent Standard Adjustment.
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