Brother PC-420 Operation Manual page 144

APPENDIX —————————————————————————————————————————————————————
Symptom
The upper thread was not threaded
correctly (for example, the spool is
not installed correctly, the spool cap
is too big for the spool being used, or
the thread has come out of the nee-
dle bar thread hook).
There are knots or tangles in the
thread.
The selected needle is not appropri-
ate for the thread being used.
The upper thread tension is too tight. Loosen the upper thread tension.
The thread is tangled, for example,
in the shuttle.
The upper
The needle is bent or blunt.
thread breaks.
The needle is incorrectly installed.
The area around the hole in the nee-
dle plate is scratched, or has a burr
on it.
The area around the hole in the
presser foot is scratched, or has a
burr on it.
The shuttle is scratched, or has a
burr on it.
A bobbin designed specifically for
this machine is not used.
The bobbin thread is incorrectly
installed.
The bobbin is scratched or does not
rotate smoothly, or has a burr on it.
The lower
thread is tangled
The thread is tangled.
or breaks.
A bobbin designed specifically for
this machine is not used.
The upper thread was not threaded
correctly.
The bobbin thread is incorrectly
installed.
The combination of fabric, thread
and needle is not correct.
The thread ten-
The presser foot holder is incorrectly
sion is incorrect.
installed.
The thread tension is incorrect.
A bobbin designed specifically for
this machine is not used.
138
Probable Cause Remedy
Correct the upper threading.
Remove any knots or tangles.
Select a needle that is appropriate
for the type of stitch being used.
Remove the tangle thread. If the
thread is tangled in the shuttle, clean
the shuttle.
Replace the needle.
Correctly install the needle.
Replace the needle plate.
Contact your retailer or the nearest
authorized service center.
Replace the presser foot.
Contact your retailer or the nearest
authorized service center.
Replace the shuttle.
Contact your retailer or the nearest
authorized service center.
Incorrect bobbins will not work prop-
erly. Only use a bobbin designed spe-
cifically for this machine.
Correctly install the bobbin thread.
Replace the bobbin.
Remove the tangled thread and
clean the shuttle.
Incorrect bobbins will not work prop-
erly. Only use a bobbin designed spe-
cifically for this machine.
Correct the upper threading.
Correctly install the bobbin thread.
Select a thread and needle that are
appropriate for the type of fabric
being sewn.
Correctly install the presser foot
holder.
Adjust the tension of the upper
thread.
Incorrect bobbins will not work
properly. Only use a bobbin
designed specifically for this
machine.
Reference
page 24
–
page 33
page 54
page 135
page 34
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page 18
page 22
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page 135
page 18
page 24
page 22
page 33
page 39
page 54
page 18