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5. Needle breakage
6. Needle thread cannot be cut.
7. Bobbin thread cannot be cut.
8. Clicks occur when needle rocking is
performed at low speed.
5-1) The needle breaks when it hits against this
side of the needle slot in the throat plate.
5-2) The needle breaks when it hits against both
sides of the needle slot in the throat plate.
6-1) The last stitch skips.
6-2) The moving knife spreads the thread loops.
7-1) The moving knife spreads the bobbin
thread.
8-1) Three metals are set to the needle bar
support base shaft rear metal section for
slide resistance. One located in the center
is free and grease on it is used up.
1)-A Needle thread tension is too high.
1)-B The needle fails to enter the needle slot
in the throat plate.
2)-A Zigzag width is wider than the needle
slot.
2)-B The needle throwing range exceeds the
needle slot since the needle throw
positioning lever has been moved too
far.
1)-A Refer to the description of "Stitch
skipping."
1)-B Thread tension is insufficient at the time
of thread trimming.
2)-A Thread tension is insufficient at the time
of thread trimming.
1)-A Bobbin thread tension is too low.
1)-A The metal in the center is free and
moves to the right or left. Then it comes
in contact with other components at the
time of needle rocking. As a result,
clicks occur.
Reduce the needle thread tension.
The needle thread tension may have been increased because of isolated idling loops. S0, also
refer to the description of "Isolated idling loops."
Adjust the needle entry point.
Decrease the zigzag width or replace the throat plate with an appropriate one.
Return the needle throw positioning lever to the home position and make the stopper work at a
position where the needle does not come in contact with the throat plate.
Increase the thread tension provided by the pre-tension disk. (6 g or higher)
Increase the thread tension provided by the pre-tension disk.
Lengthen the stroke of the needle thread feeding device. (The needle thread is tensed by
steeply bending the thread path.)
Increase the bobbin thread tension, then balance the needle thread and bobbin thread.
Refe to (5) Removing/installing the needle bar support base shaft (asm.).
Trouble Cause 1 Cause 2 Corrective measure and adjusting procedure
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