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Thread Break ⑦ Use of low-quality thread
(loose thread twist, uneven
thread thickness, bad thread
winding, too weak or too
old thread, etc.)
⑧ Use the thread twisted in
the right direction (S-shape
twist)
⑨ Too strong tension of the
upper and lower thread
⑩ Uneven tension of the
upper and lower threads
⑪ Excessive tension and
stroke of the thread take-up
lever spring
■ Replace the thread for high-
quality one
■ Use the thread twisted in
the left direction (Z-shape
twist)
■ Adjust the tension
■ Adjust the tension
■ Adjust the tension and
stroke of the thread take-up
spring
Check the thread used
※Tips for thread
selection
■ The thread used
should be soft and
constant in thickness.
Its tension should be
stable.
■ The thread twist shall
be tight and be made
in the left direction.
■ Z-shape twist (left
direction)
■ S-shape twist (right
direction)
Corrective Action and Check PointCause of TroubleType Remarks
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