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Troubles Causes Checking Corrective measures
4. Irregular stitches Stroke of the thread take-up
spring is improper.
Thread paths have been
poorly finished.
Bobbin fails to move
smoothly.
Bobbin thread tension is too
low.
Bobbin has been wound too
tightly or too weakly.
Check the stroke of the
thread take-up spring.
Check the finish of the
respective thread paths.
Check the change of the
bobbin thread tension.
Check the state of bobbin
winding.
Adjust the thread take-up spring
to move to approximately 1 mm
from the initial position when
hook draws thread maximumly.
Finish with a fine emery paper
or buff.
Replace the bobbin or hook.
Increase the tension of the
bobbin thread.
Decrease the tension applied to
the bobbin winder or increase
it.
Adjustment of the thread take-up spring
• Irregular stitches will be improved when decreasing the tension and the stroke.
* When using LU-1508H with the electro-motor, the correct stop-position cannot be
obtained and trouble in sewing may occur since the inertia force of the handwheel is
large.
In this case, use the motor with the stop-position at 1 Pos or replace the handwheel
with “21332804”.
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