Brother BAS-705 Instruction Manual page 79

10. TROUBLESHOOTING
Problem
Upper thread is not
trimmed.
Thread jamming.
Thread jamming at the
final stitch.
Upper thread breaks at
the final stitch.
Cause
Fixed knife is blunt.
Movable knife does not
pick up the thread.
The movable knife does not pick
up the thread because of skipped
stitches at the sewing end.
Movable knife position is
incorrect.
Sub-tension is too weak.
Thread trailing length is
too long.
Thread take-up spring
tension and height are
incorrect.
Incorrect needle and
rotary hook timing.
Shuttle race thread
guide is not separating
the threads.
Thread scraps sticking
to surface of race.
Upper tension is too
weak.
Too much thread.
Incorrect height or
tension of thread take-up
spring.
Incorrect thread release
cylinder operation.
Sub-tension is too strong.
Thread take-up spring
tension and height are
incorrect.
Damaged or burred shuttle race,
needle hole plate, needle, movable
knife or shuttle race thread guide.
Check
Fixed knife blade
Shuttle race thread
guide position
Needle bar lift amount
Skipped stitches at
sewing end
Movable knife position
Sub-tension
Sub-tension
Thread take-up spring
tension and height
Needle bar lift amount
Shuttle race thread
guide position
Surface of shuttle hook
Upper tension
Thread amount
Tension and height of
thread take-up spring
Thread release cylinder
operation
Sub-tension
Thread take-up spring
tension and height
Damage or burring
76
Remedy
Sharpen or replace the
fixed knife.
Adjust the position of the
shuttle race thread guide.
Adjust the needle bar lift
amount.
Refer to "Skipped
stitches occur".
Adjust the position of the
movable knife.
Turn the sub-tension nut
to adjust the tension.
Thread resistance along
thread path is too small.
Adjust the thread trailing
length to 45 mm.
Adjust the tension and
height of the thread
take-up spring.
Adjust the needle bar lift
amount.
Adjust the position of the
shuttle race thread guide.
Clean all thread scraps
and dust from the race
Make the upper tension
stronger.
Reduce the thread
amount.
Decrease the tension or
raise the height of the
thread take-up spring.
Adjust the thread
release cylinder so that it
operates smoothly.
Decrease the subtension.
Decrease the tension or
raise the height of the
thread take-up spring.
File smooth or replace
the affected part.
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BAS-705