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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
12-4) Throat plate
4-A)
A dent exists on the flat part between
the rear edge of the needle hole and
feed dog groove.
Dent
Repair or replace the throat plate, since such dent
causes chain-off thread to slip out.
12-5) Presser foot
5-A)
The rear pressure foot is indented and
not flush with the presser foot sole, so
that it cannot hold chain-off thread.
Replace it, or correct it to make it flush with the
presser foot sole.
12-6) Main feed dog
6-A)
The leading edge of the main feed dog
is too sharp and cuts chain-off thread.
Buff the leading edge of the main feed dog.
12-7) Double hooking
7-A)
The needle thread is not drawn up fully
because of the insufficient returning
amount of the double chain looper or
cam timing is early or wrong threading.
Refer to the related Standard Adjustment for the
returning amount of the double chain looper or
cam timing. See the threading digram for correct
threading.
7-B)
If the feed pitch is too small, the cam
timing will be advanced.
Retard the cam timing.
12-8) Thread tension
8-A)
The needle is bend or chain-off thread
runs back due to excessive needle
thread tension.
Reduce the needle thread tension.
8-B)
Both the needle thread and looper
thread tension are too low.
Slightly decrease the both tensions.
13. Overlocking needle thread is
loose.
13-1) Position of the
needle thread take-
up guide and needle
thread guide
1-A)
They are positioned too high, and the
thread take-up draws out excessive
needle thread.
Refer to the pertinent Standard Adjustment.
13-2) Thread tension
2-A)
The thread tension balance has been
disturbed.
Refer to the Standard Adjustment for the looper
thread take-up components, and increase the ten-
sion if necessary.
13-3) Needle
3-A)
The needle is too thin for the thread
used.
Replace it with a proper one.
