12. TROUBLESHOOTING
RH-9820
123
Problem Cause
Remedy
Page
Needle is bent.
Replace with a new needle.
30
Needle, looper and spreader adjustment
is incorrect.
Adjust correctly.
71
76 - 81
Needle guard is covering the needle too
far.
Adjust the needle guard.
79
Broken needle
Needle is too thin.
Select a needle that is suitable for the
sewing conditions.
55
Upper movable knife is blunt.
Replace the upper movable knife with a
new one.
96, 97
Upper movable knife does not move to
the full stroke because air pressure is
too weak.
Adjust the air pressure.
25
Upper movable knife is not picking up
the upper thread.
Install the upper movable knife so that it
cuts only one side of the upper thread
loop.
97
Upper movable knife is not picking up
the upper thread because the last stitch
is being skipped.
Refer to the remedies given under
“Skipped stitches occur” in this
troubleshooting chart.
122
Upper thread is not cut.
Upper movable knife position is
incorrect.
Adjust the position of the upper movable
knife.
97
Movable knife is blunt.
Replace the movable knife with a new
one.
99, 104
Movable knife does not move to the full
stroke because air pressure is too weak.
Adjust the air pressure.
25
Movable knife position is incorrect.
Adjust the position of the movable knife
or the thread handler.
100, 103
105
Lower thread is not cut.
Cutting pressure for lower thread
trimming is too weak.
Adjust to an appropriate cutting
pressure.
100, 104
Lower thread is not being held.
Adjust the lower thread nipper (-01
specifications) or the lower thread
presser (-02 specifications).
101, 103
108
Upper thread length is too short after
trimming.
Adjust the sub tension.
55
Not enough upper thread is being fed
out.
Adjust the amount of upper thread being
fed out.
95
Thread unravelling at
sewing start
Upper thread loops are uneven.
Set slow start and bar tacking.
42, 43
Cutting pressure is too weak.
Adjust the cutting pressure so that it is
strong enough.
90
Knife and hammer are not contacting
properly.
Grind the hammer surface.
84
Material is not being cut
cleanly.
Knife is blunt.
Replace the knife with a new one.
87
Upper thread tension is too strong or too
weak.
Adjust the upper thread tension to the
correct tension.
55
Lower thread tension is too strong or too
weak.
Adjust the lower thread tension to the
correct tension.
55
Poor thread tightening
Tension or stroke of thread take-up
spring is incorrect.
Adjust the tension and stroke of the
thread take-up spring.
55