Brother PR-620 Operation Manual page 219

APPENDIX —————————————————————————————————————————————————————
Symptom
Sliding surface on hook is not
smooth. There are burns on it.
The thread is loose in the hook
area.
The play between the hook and
the race is too much.
The hook does not rotate
smoothly.
The space between the hook
stopper and the hook cannot be
adjusted.
The upper thread is not threaded
correctly.
The upper thread
breaks.
Upper thread is not positioned
in upper or middle thread guide.
There are knots or tangles in the
thread.
The upper thread tension is too
high.
The lower thread tension is
incorrect.
The thread does not roll out of
the bobbin case smoothly.
The bobbin case is damaged.
The bobbin thread is not wound
correctly.
A bobbin designed specifically
for this machine is not used.
202
Probable Cause
1
1 Hook race area
Remedy
Consult your nearest authorized
dealer.
Remove the loose thread. If the
thread is tangled in the hook,
clean the hook.
Consult your nearest authorized
dealer.
Remove lint, and clean and
apply oil.
Consult your nearest authorized
dealer.
Pull the upper thread by hand
from below the presser foot, and
check that the thread moves
smoothly. If the thread does not
move smoothly, it is not
correctly threaded.
Un-thread the machine and
re-thread the machine.
Make sure the thread is correctly
positioned in the needle bar
thread guide.
Make sure thread passes
completely under upper and
middle thread guide.
Remove any knots or tangles.
Decrease the upper thread
tension.
Adjust the lower thread tension.
Replace the bobbin case with a
new one.
Check that the bobbin is wound
so that it about 80% full and that
the thread is evenly wound. If
the bobbin is not correctly
wound, replace the bobbin with
one that is correctly wound or
rewind the bobbin.
Use the correct bobbin.
Reference Page
p.193
p.193, 196
p.35-38
p.36-37
p.86
p.85
p.15
p.15
p.15