Troubleshooting - Brother LK3-B438E MKII Instruction Manual

16. TROUBLESHOOTING

Problem
Button clamp does
not rise.
Button clamp does
not drop.
Button clamp lift
amount is incorrect.
Thread wiper does
not operate correctly.
Lower thread winds
to one side.
Lower thread
winding amount is
incorrect.
Threads comes
unthreaded.
Cause
Button clamp lifter
amount is too great.
Presser is contacting
thread wiper.
Presser lifter link is
not moving back.
Incorrect position of
button clamp holder
hook assembly
The thread wiper is
obstructing the
needle.
Thread wiper
position is incorrect.
Bobbin winder thread
tension stud height is
incorrect.
Bobbin presser
position is incorrect.
Stitches being
skipped at the sewing
start.
Uneven upper thread
length.
Upper thread is too
short.
LK3-B438E Mark II
Check
Distance between
button clamp and top
of needle plate
Thread wiper standby
position
Link return spring is
unhooked.
Distance between
button clamp and top
of needle plate
Clearance beween
thread wiper and
needle tip
Thread wiper
position
Bobbin winder thread
tension stud height
Thread winding
amount
Refer to "Skipped
stitches occur"
Upper thread length
Thread take-up lever
stroke
16. TROUBLESHOOTING
Remedy
Adjust the height of
the button clamp to
within 17 mm.
Adjust the position of
the thread wiper.
Hook the link return
spring properly.
Adjust the button
clamp lift amount.
Adjust the height of
the thread wiper.
Adjust the operating
distance of the thread
wiper.
Adjust the height of
the thread tension
stud.
Adjust the position of
the bobbin presser.
Refer to "Skipped
stitches occer".
Adjust the sub-
tension.
Adjust the thread
take-up lever stroke.
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