JUKI MO-6000S series Engineer's Manual page 82

Trouble
From the previous page
4. The needle point is crushed. (Double chain
stitch needle)
5. Overlocking needle thread stitches are
skipped.
The lower looper fails to catch needle thread
loops.
Right side Wrong side
Case (1)
Needle guards
Needle No.
Thread tension
Height of the feed dog or needle
Needle guard
Contact with the looper
Lower looper
Adjustment of the loopers.
Needle thread presser
Needle
Needle guards
to the next page
Case(2)
A needle guard has been improperly positioned, causing
the needle point to strike it.
The needle is too thin for the materials.
The thread tension is too high.
The feed dog is too high, or the needle is too low,
causing the needle to deflect with resultant needle
breakage.
The needle guard C is too low, or its longitudinal position
is not correct.
The tilt of the looper is not correct. The longitudinal
motion of the looper is not correct.
The blade point has defective shape and does not catch
needle thread loops.
The clearance or the amount of return is not correct.
The duration in which the presser holds the needle
thread is not correct, and unstable loop result.
The needle is bent or improperly oriented. A needle or
DC x 1 is used.
Incorrect height or clearance prohibits correct guide for
the needle. If a needle guard is too high, loops are
crushed with consequent stitch skipping.
Check and Corrective measures
Refer to the pertinent Standard Adjustment.
Replace the needle with a thicker one.
Reduce the thread tension.
Refer to the related Standard Adjustment.
Increase the height of the needle guard (C). Check the
clearance between the needle and needle guard.
Check the tilt of the looper. Correct the longitudinal motion
of the looper, and increase the clearance between the
looper and needle when the looper reaches its most
retracted position.
Replace the lower looper.
Refer to the relevant Standard Adjustment.
Refer to the pertinent Standard Adjustment.
Replace the bent needle. Correctly orient and attach the
needle.
Use a DC x J27 needle for a stretchy thread.
Refer to the pertinent Standard Adjustment.
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