Brother LB6770 PRW Operation Manual page 159

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Symptom
Stitches are
skipped.
A high-pitched
noise is made
while sewing.
The thread does
not pass through
the eye of the
needle.
The stitch is not
sewn correctly.
The fabric does not
feed.
The fabric feeds in
the opposite
direction.
The needle
threader lever does
not lower to the
correct position.
The sewing lamp
does not come on.
Nothing appears in
the LCD.
Probable Cause
The needle is incorrectly installed. Correctly install the needle.
Dust has accumulated under the
needle plate or in the bobbin case.
Dust has accumulated in the feed
dogs or in the bobbin case.
The upper thread was not
threaded correctly.
The bobbin case is scratched, or
has a burr on it.
A bobbin designed specifically for
this machine is not used.
The needle has not been raised to
the correct position.
The needle is incorrectly installed. Correctly install the needle.
The presser foot that is used is not
appropriate for the type of stitch
that you wish to sew.
The thread tension is incorrect.
The thread is tangled, for example,
in the bobbin case.
The feed dogs are lowered.
The stitch is too fine.
The presser foot that is used is not
appropriate for the type of stitch
that you wish to sew.
The thread is tangled, for example,
in the bobbin case.
The feed mechanism is damaged.
The needle has not been raised to
the correct position.
The sewing lamp is damaged.
The machine is not turned on.
The brightness of the LCD is either
too light or too dark.
Remedy
Remove the needle plate cover and
clean the race.
Clean the race.
Correct the upper threading.
Replace the bobbin case.
Contact your dealer or the nearest
authorized service center.
Incorrect bobbins will not work
properly. Only use a bobbin
designed specifically for this
machine.
Press the needle position button.
Attach the presser foot that is
appropriate for the type of stitch that
you wish to sew.
Adjust the tension of the upper
thread.
Remove the tangle thread. If the
thread is tangled in the bobbin case,
clean the race.
Slide the drop feed lever to the right.
Lengthen the stitch length.
Attach the presser foot that is
appropriate for the type of stitch that
you wish to sew.
Remove the tangled thread. If the
thread is tangled in the bobbin case,
clean the race.
Contact your dealer or the nearest
authorized service center.
Press the needle position button.
Contact your dealer or the nearest
authorized service center.
Turn on the machine.
Adjust the brightness of the LCD.
Reference
page 41
page 152
page 152
page 32
-
page 22
page 32
page 41
page 70
page 59
page 152
page 102
page 59
page 70
page 152
-
page 32
-
page 17
page 163
Troubleshooting 157
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