Brother BAS-341F Instruction Manual page 64

15. TROUBLESHOOTING
Problem
Unstable upper thread
length
Unstable needle up
stop position
57
Cause
Improper tension and height
of thread take-up spring
Improper adjustment of
sub tension
Needle up stop position
fluctuates.
Fixed knife is blunt.
Inadequate adjustment
of V belt tension
Electrical trouble
Check
Thread take-up spring
tension and height
sub tension
See "Unstable needle
up stop position".
Fixed knife blade
Tension pulley position
Refer to the details for [E.
22] in the error code table.
BAS-341F, 342F
Remedy
Adjust the tension and
height of the thread take-
up spring.
Adjust the sub tension.
Sharpen or replace the
fixed knife.
Adjust the tension of the
V belt using the tension
pulley
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