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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
From the previous page
7-5)
Amount of thread
5-A)
Excessive upper looper thread is fed,
producing stack of thread.
Slack of thread
Needle
Slightly lower the looper thread take-up (left)
to decrease the amount of thread. Shorten the
upper looper thread guide (right) to decrease the
amount of thread.
Slightly raise the looper thread take-up (right) to
decrease the amount of thread.
If the thread tension is not enough, increase it.
8. Double chainstitches are
skipped.
The double chain looper tails
to catch needle thread loops.
Two stitches
are skipped.
Viewed from the
wrong side
8-1)
Needle height
1-A)
If the needle is not correct, stitch skip-
ping occurs even when the returning
amount of the chain looper is correct.
Refer to the pertinent Standard Adjustment.
8-2)
Needle
2-A)
The needle is bent or attached with
wrong orientation. DC×1 needle is used.
Replace the bent needle. (Remove the cause for
the needle bend.) Correct the orientation of the
needle. Use a DC×27 needle (with a better recess
configuration).
8-3)
Double chain looper
3-A)
The lower part of the blade point has
been deformed, and the blade point
fells loops.
Replace the double chain looper.
8-4)
Adjustment of looper
4-A)
Clearance or returning amount is not
correct.
Refer to the pertinent Standard Adjustment.
8-5)
Thread tension
5-A)
The thread tension is too high, prevent-
ing formation of good loops.
Reduce the tension. However, be careful not to
reduce the tension too much, otherwise unstable
loops will result.
8-6)
Needle guard
6-A)
A needle guard is too high, and loops
are crushed. The clearance is too big,
causing the needle to shake.
Refer to the pertinent Standard Adjustment.
8-7)
Needle heat
7-A)
The thread breaks due to heat gener-
ated on the needle, depending on the
type of materials, number of plies, and
sewing speed.
Use a thinner needle. Reduce the sewing speed.
Check the coolant if necessary.
