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Trouble Case (1) Case (2) Check and Corrective measures
16. The looper thread cannot
be passed.
16-1) Thread path pipe 1-A) The pipe is clogged with dust. Remove dust with a threader supplied with the
machine.
1-B) Scratches inside the pipe Pull the thread from the looper by hand to check
whether it is caught by any part.
1-C) The pipe is lubricated due to malopera-
tion.
Pass a thick thread (cotton thread count of which
is #20 or lower) through the pipe to remove oil.
1-D) The piston lip of the pump is applied
with an excessive amount of grease. As
a result, the grease enters the pipe.
Take the aforementioned corrective measure.
16-2) The pump pressure is
too low. No air ows
inside the pump.
2-A) The pump piston does not move
smoothly.
Apply a small amount of grease to the periphery of
the piston lip. If the piston lip has worn out, replace
it with a new one.
2-B) The air tube has crushed. Pull out the tube from the pump. Twist it to correct
the bend.
16-3) The lever does not move
if it is operated. (It does
not move to the looper
side.)
3-A) An extra force is applied to the lever to
deform the sheet metal.
Correct the deformed part of the lever, or replace it
with a new one.
17. Faulty needle threader 17-1) The needle cannot be
threaded.
1-A) The hook has bent and lost its lateral
center. As a result, the needle threader
cannot enter the needle eyelet.
Correct the hook so that it is positioned equidis-
tantly from the right and left needle guide plates. If
this corrective measure cannot be taken, replace
the needle threader with a new one.
1-B) The hook radius has increased. As a re-
sult, the thread slips o the hook before
the needle threader enters the needle
eyelet.
Replace the needle threader with a new one.
1-C) The hook has bent downward and pre-
vents the needle from being passed to
the end.
When the hook is correctly posi-
tioned, the lower side of the hook
is aligned with the lower side of the
needle guide plate. If the corrective
measure is hard to be taken, replace
the needle threader with a new one.
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