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Trouble
① When the needle is inserted in a wrong way.
Stitch
skipping
a. The needle is not entirely inserted into the needle
bar.
b. The needle eye is not facing straight to the opera-
tor.
c. The needle is facing backwards.
② When the needle itself is not suitable.
a. The needle is bent.
b. The quality of the needle is not good.
c. The needle is too thin for the thread.
d. Blunt needle is used.
③ When the hook blade point is not sharp enough or
damaged.
④ When the timing of the sewing hook and the needle
is not matched.
⑤ When the height of the needle bar is not correct.
⑥ When the clearance between the needle and the
sewing hook is too great.
① When the needle thread tension is too low.
Loose
stitch
② When the tension of the thread take-up spring is too
low.
③ When the tension of the bobbin thread is too high.
④ When the timing of the sewing hook and the needle
is not matched
⑤ When the thread is too thick for the needle.
⑥ Thread slips out of the rotary tension.
① When the bobbin thread tension is too low.
Irregular
stitch
② When the bobbin thread is not wound correctly.
tightness
③ When there is a scratch on the thread path of the
sewing hook, bobbin case, thread take-up lever or
any other parts.
① When the needle is bent.
Needle
breakage
② When the quality of the needle is not good.
③ When the needle is not entirely inserted into the
needle bar.
④ When the needle hits the sewing hook.
⑤ The needle is too thin for the sewing material and
thread.
⑥ The needle hole in the throat plate is too narrow.
⑦ The needle hits against the throat plate.
⑧ The needle hits against the presser foot.
Cause
– 59 –
Corrective measures
Fully insert the needle.
Let the needle eye face straight to the
operator.
Let the long groove on the needle face
to the operator.
Replace it with a new needle.
Use a needle of good quality.
Use a suitable needle or thread.
Replace it with a new needle.
Resharpen the hook or replace it.
Adjust the timing properly.
Adjust the height of the needle bar.
Adjust the clearance.
Increase the needle thread tension.
Increase the tension of the spring.
Decrease the bobbin thread tension.
Adjust the timing correctly.
Use a suitable needle or thread.
Increase the tension of the pretension
disk.
Increase the bobbin thread tension.
Wind up the bobbin thread evenly.
Remove such a scratch or replace the
component.
Replace it with a new needle.
Use a needle of good quality.
Insert the needle into the needle bar as
far as it will go.
Adjust the timing and clearance between
the needle and the sewing hook and
also the position of the needle guard.
Replace a suitable needle.
See
page
4
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21
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16
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16
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12
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