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Trouble Case (1) Case (2) Check and Corrective measures
6. Lower looper stitches are
skipped
6-1) Threading 1-A) The thread has been entangled with a
thread guide. Threading has not been
done correctly.
Refer to the threading diagram.
(Refer to the Instruction Manual)
The upper looper does not catch
the lower looper thread.
6-2) Upper looper 2-A) The blade point has a bad shape, and
fails to catch the loops.
Replace the upper looper with badly deformed
blade point.
6-3) Lower looper 3-A) The clearance between the needle and
the back of lower looper are not correct.
Replace the lower looper having a deformed tip.
6-4) Adjustment of the
loopers
4-A) The feed amount of the lower looper,
height of the upper looper, or clearance
produced at time of crossing of the upper
and lower loopers is not correct.
Refer to the pertinent Standard Adjustment.
6-5) Thread amount 5-A) Too much lower looper thread is fed, giv-
ing slack of thread.
Shift the thread guide of the looper thread take-
up to the right.
7. Upper looer thread stitches
are skipped
7-1) Threading 1-A) The thread has been entangled with a
thread guide. Threading has not been
done correctly.
Refer to the threading diagram.
(Refer to the Instruction Manual)
The needle does not take the
upper looper thread.
7-2) Needle height 2-A) The needle, if positioned too high or low,-
may fail to catch the upper looper thread.
Refer to the pertinent Standard Adjustment.
7-3) Needle 3-A) The needle is bent or crushed, in its point. Replace the needle. At this time, be sure to
eliminate the cause for such needle bend or
needle point crush.
7-4) Adjustment of the
upper looper
4-A) The height of the blade point is not cor-
rect,making the upper looper unable to
properly pass the thread to the needle.
The clearance between the needle and
the back of the upper looper is not correct.
Refer to the pertinent Standard Adjustment.
7-5) Amount of thread 5-A) Excessive upper
looper thread is fed,
producing stack of
thread.
Shift the thread guide of the looper thread take-
up to the right.
If the thread tension is not enough, increase it.
Right
side
Wrong
side
Right
side
Wrong
side
Needle
Lower
looper
thread
Upper
looper
Needle
Slack of
thread
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