–55 –
(2) With regard to thread trimming
Troubles
Causes
Checking
Corrective measures
One or serveral stitches
skip at the start of sewing.
Thread remaining at the
needle top after thread
trimming is short.
Bobbin thread is not
clamped.
Needle is too thick.
Needle hole in the feed
dog is too large.
Pressure of the presser
foot is too low.
Stitches are too small.
Check the routing of
needle thread.
Thread tension given by
the tension controller
No.1 is too high.
Check the rising amount
of the thread tension disk
No.2 at the time of thread
trimming.
Thread trimming timing is
excessively advanced.
There are scratches on
the moving knife and the
hook.
Presser foot drops from
cloth at the time of thread
trimming.
Position of the clamp
spring.
Pressure of the clamp
spring is too low.
There are scratches on
the clamp spring.
Needle thread removes
bobbin thread.
T h r e a d t h e n e e d l e t h r e a d
correctly. Adjust so that abnormal
needle thread tension is not
applied.
Decrease the tension given by the
tension controller No.1.
Adjust so that the disk is raised
by means of the thread release
solenoid.
Refer to “10. TIMING CHART”.
Polish with buff or replace the
part.
Perform thread trimming on cloth.
Refer to "(18) -7) Position of the
clamp spring".
Refer to "(18) -7) Position of the
clamp spring".
Replace the clamp spring with a
new one.
Increase or decrease the tension
of the tension controller No.1.
Replace the needle with a thinner
one.
Replace the feed dog with an
optional one with small needle
hole.
Increase the pressure of the
presser foot.
Do not pass thread through the
thread presser section of the
thread guide on the needle bar.
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