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Trouble
① Clearance provided between the nee-
5. Stitch skipping often
occurs.
② Position of the inner hook holder
③ The needle is bent.
④ The needle thread after thread trim-
① The needle thread tension is not high
6. The needle thread
comes out on the
② The needle thread after thread trimming
wrong side of the
material.
① The knife has been improperly posi-
7. Threads break at
time of thread trim-
ming.
① Stitch skipping at the 1st stitch.
8. Thread end of the
1st stitch comes out
② Needle used and thread used are
on the right side of
the material.
③ Intermediate presser is not properly
④ The direction of air blower is incorrect.
① The clearance provided between the
9. The needle thread
is entangled in the
inner hook holder.
① The bobbin runs idle excessively.
10. The knotting section
of bobbin thread
② Bobbin thread tension is too low.
at 2nd stitch at
③ The needle thread tension at 1st
the sewing start
appears on the right
side.
Cause
dle and the hook is not correct.
against the needle is not correct.
ming is too long.
enough.
is too long.
tion.
thick in terms of the inner diameter of
the intermediate presser.
positioned in terms of the needle.
As a result, needle thread at the tip
of needle cannot be clamped with the
disc presser.
inner hook holder and the inner hook
is too small.
stitch is too high.
◦ Adjust the clearance between the needle and the
hook.
◦ Adjust the position of the inner hook holder
against the needle.
◦ Replace the bent needle.
◦ Decrease the tension of the thread take-up
spring.
◦ Increase the tension of the thread tension con-
troller No. 1.
◦ Increase the needle thread tension.
◦ Increase the tension of the thread tension con-
troller No. 1.
◦ Correct the position of the knife.
◦ Increase the length of needle thread remaining
at the needle after thread trimming.
◦ Change the current intermediate presser with
another one which has a larger inner diameter.
◦ Adjust the eccentricity between intermediate
presser and needle so that needle enters in the
center of intermediate presser.
◦ Adjust the air-blowing direction of the air blow-
er according to the direction of sewing so that
the needle thread at the tip of needle can be
clamped with the disc presser.
◦ Adjust the clearance provided between the inner
hook holder and the inner hook appropriately
according to the thickness of needle thread to be
used.
◦ Adjust the height of idling prevention spring of
the bobbin case appropriately.
◦ Increase the bobbin thread tension.
◦ Decrease the needle thread tension at 1st stitch.
– 65 –
Corrective measures
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