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8.
CAUSES OF TROUBLES AND THE CORRECTIVE MEASURES FOR MB-377
Troubles Causes Corrective measures
1. Needle thread breaks
after the machine
stops.
Lifting amount of the button clamp jaw
unit is excessive.
The nipper has been improperly
adjusted.
The thread pull-off lever has been
improperly adjusted.
Adjust the nipper with the nipper bar block.
Properly adjust the tension lever.
Adjust the lifting amount of the button clamp jaw
lever to 8 mm.
The tension lever has been improperly
adjusted.
Properly adjust the rocker shaft of the thread pull-
off lever.
2. The machine forms a
seam after it has run for
a while instead of
forming it from the start
of sewing.
Tension of the thread tension guide on
the face plate is excessive.
The tension lever has been improperly
adjusted.
Adjust the thread tension guide on the face plate
so that it provides a lower tension.
Properly adjust the tension lever.
Adjust the nipper with the nipper bar block.
Advance the timing of the knot-tying plate.
(Adjustment of the knot-tying notch.)
3. The last back-tack
stitch is poorly tensed.
The nipper has been improperly
adjusted.
Timing of the knot-tying plate is
incorrect.
4. Length of thread
remaining, after thread
trimming, on the wrong
side of the material
varies.
Position of the moving knife is not
correct.
Lifting amount of the button clamp jaw
unit is excessive.
Adjust the position of the moving knife when the
machine completes stop-motion.
(10.5 to 12.5 mm)
Adjust the lifting amount of the button clamp jaw
lever to 8 mm (for コ -shaped tacking and Z-
shaped tacking) or 10 mm (for X-shaped tacking).
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