Brother RH-9800 Instruction Manual page 65

Problem
Upper thread is not cut.
Lower thread is not cut.
Thread slips out of the
needle at the sewing
start.
Material is not being cut
cleanly.
Cause
Knife is blunt.
Knife does not move to the full
stroke because air pressure is too
weak.
Upper thread trimmer knife is not
picking up the upper thread.
Movable knife is not picking up
the needle thread because the
last stitch is being skipped.
Movable knife position
incorrect.
Knife is blunt.
Knife does not move to the full
stroke because air pressure is too
weak.
Movable knife position
incorrect.
Thread nipper spring force is too
weak.
Upper thread length is too short
after trimming.
Needle and looper adjustment is
incorrect.
Not enough upper thread is being
fed out.
Cutting pressure is too weak.
Knife and cutting block are not
contacting properly.
Knife is blunt.
Cutter arm operation time is too
short.
RH-9800
11. TROUBLESHOOTING
Remedy
Replace with a new knife.
Adjust the air pressure.
Install the upper thread trimmer
knife so that it cuts only one side
of the upper thread loop.
Refer to the remedies given under
"Skipped stitches occur" in this
troubleshooting chart.
is Adjust the position of the movable
knife or the loop spreader.
Replace with a new knife.
Adjust the air pressure.
is Adjust the position of the movable
knife or the loop spreader.
Adjust the force of the thread
nipper spring.
Install the upper thread trimmer
knife so that it cuts only one side
of the upper thread loop.
Adjust the needle bar height or
the looper and spreader height.
Adjust the amount of upper thread
being fed out.
Adjust the cutting pressure so that
it is strong enough.
Grind the cutting block surface.
Replace with a new knife.
Make the operation time longer by
changing the memory switch
setting.
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