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10. TROUBLES AND CORRECTIVE MEASURES
(1) With regard to sewing
Trouble Cause (1) Cause (2) Checking order and adjusting procedure Page
1. Needle thread breakage 1-1) Attaching needle is wrong.
1-2) Threading is wrong.
1-3) There are scratches on the
thread path sections.
1-4) Adjustment of thread tension
components is wrong.
1)-A Direction of needle is wrong.
1)-B Height of needle is wrong.
1)-C Needle is bent.
3)-A There are scratches on thread
take-up spring, thread take-up
lever, thread tension disk,
throat plate, needle bar thread
guide, etc. Or, thread path has
worn out.
3)-B There is a scratch on the blade
point of hook or periphery of
hook.
4)-A Bar-tacking thread tension is
too high or too low.
4)-B Thread tension at parallel is too
high or too low.
4)-C Tension or stroke of thread
take-up spring is improper.
Attach the needle so that the indented part of the needle faces to this
side as observed from the front of the sewing machine.
Insert the needle until the top end of the shank of needle comes in
contact with the upper end of the needle hole of needle bar.
Place the needle on the flat section of the table or the like, press the
shank section with fingers and turn the needle to check the deflection
of the needle tip. If the needle is deflected, replace it.
Correctly thread the needle thread.
Correct the scratch with buff, or replace the part. Especially take care
of the finish of the lower face of needle hole in the throat plate.
Correct the scratch with buff, or replace the part.
Checking the balance of stitches at bar-tacking section (needle thread
on the right side and bobbin thread on the wrong side), adjust the
tension.
Make the bobbin thread tension proper. Confirming the crest of seam
at parallel section of stitches, adjust the tension. (Refer to the Instruction
Manual.)
Standard stroke : 8 to 10 mm
Standard tension : 6 to 10g (In case of purl stitching)
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