JUKI LU-1510N Engineer's Manual page 72

Troubles
4 Irregular stitches
5 Loose stitches at the time
of corner stitching
* When the electronic stop motor is used with LU-1508NH or LU-1590NH, the correct stop position
cannot be obtaoned since the force of inertia of the handwheel is large, and sewing trouble may
occur.
In this case, use the sewing machine making the motor stop position "1pos", or replace the handwheel
with one, "21332804".
Causes
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 tight or too weak.
D i r e c t i o n o f s e t t i n g
bobbin is reverse.
Needle thread on the
stopping side is drawn
o u t m o r e t h a n i s
necessary.
Adjustment of the thread take-up spring
™ Decrease the tension of the thread take-up spring and decrease the stroke of
the spring to improve irregular stitches.
– 68 –
Checking
Check the stroke of the
thread take-up spring.
Check the finish of the
respective thread paths.
Check the change of
bobbin thread tension.
Check the state of bobbin
winding.
Check the setting.
Check the stroke of the
thread take-up spring.
Check the hook timing.
Corrective measures
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 the hook.
Increase the tension of the bobbin
thread.
Decrease or increase the tension
applied to the bobbin winder.
Properly set the bobbin.
In crease the stroke of the thread
take-up spring.
Retard the hook timing.
Use the optional walking foot.
(Top divided type)