JUKI MB-1373 Engineer's Manual page 27

Adjustment Procedure
1. Adjust so that stop-motion hook
disc at the stop-motion position.
2. Make adjustments, after tilting the machine head and removing the
bed oil shield, by loosening too nuts
back and forth. When tightening nuts
stud almost horizontal.
(Caution) 1. The thread trimming connecting mechanism should
be returned with button clamp pressure spring
of the button clamp. If button clamp pressure spring
is detached, the pressure will not be adequate to
normally return the thread trimming connecting
mechanism.
2. To carry out the adjustments described in each
paragraph with button clamp pressure spring
the button clamp removed, it is necessary the
machine not be running.
Adjustment Procedure
Bend thread separating claw
comes in contact with stop-motion
and moving connecting screw
, be sure to position joint
to adjust its height.
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Results of Improper Adjustment
If the adjusted distance between the
connecting link (front) and the end of
the slot in the throat plate is smaller:
o The moving knife will overrun at the
time of stop-motion. As a result, the
thread separating claw may come
into contact with the counter knife
or yoke slide, resulting in breakage
of the thread separating claw,
counter knife and yoke slide.
o The thread trimming timing will be
advanced. As a result, the last stitch
will be inadequately tensed (the
thread will be prone to fray) or
thread trimming failures will be likely
of
to occur, such as a simultaneous
trimming of two threads due to faulty
separation of the threads and
trimming of neither thread.
If the adjusted distance between the
connecting link (front) and the end of
the slot in the throat plate is larger:
o The thread separating claw may
come into contact with the yoke
slide insert while the machine is
running, resulting in breakage of the
thread separating claw.
o The thread trimming timing will be
delayed. As a result, a longer thread
will remain on the wrong side of the
fabric after thread trimming.
Results of Improper Adjustment
o If the thread separating claw is too
high, the claw may fail to separate
the thread on the needle from that
on a fabric. As a result, thread may
not be trimmed, or both threads
will be trimmed together, causing
thread slippage from the needle in
the subsequent stitching start.