Brother BAS-326G Service Manual page 149

10. TROUBLESHOOTING
Problem
Upper thread breaks.
Lower thread breaks.
Skipped stitches occur.
Needle is broken.
Thread jamming.
142
Cause
Upper thread tension is too strong.
Needle is incorrectly installed.
Thread is too thick for the needle.
Thread take-up spring tension and
height are incorrect.
Damage or burring of the rotary hook,
needle hole plate or needle.
Thread breaking from heat (Synthetic
thread)
Thread is threaded incorrectly.
Lower thread tension is too strong.
Damage to corners of needle hole plate
or bobbin case.
Clearance between needle and rotary
hook tip is too great.
Needle and rotary hook timing is
incorrect.
The driver is covering the needle more
than necessary.
Needle is bent.
Needle is incorrectly installed.
Clearance between needle and rotary
hook tip is too great.
Needle is bent.
Needle deflection
Needle is too thin.
Thread take-up spring tension and
height are incorrect.
Needle and rotary hook timing is
incorrect.
Shuttle race thread
separating the threads.
Adjust the upper thread tension.
Install the needle correctly.
Select a thread that matches the needle.
Adjust the tension and height of the
thread take-up spring.
Repair or replace the problem part.
Use a cooling tank.
Thread the thread correctly.
Adjust the lower thread tension.
Repair or replace the problem part.
Adjust the needle clearance.
Adjust the needle bar lift amount.
Adjust the driver needle guard.
Replace the needle.
Install the needle correctly.
Adjust the needle clearance.
Adjust the needle bar lift amount.
Replace the needle.
Select a needle that is suitable for the
sewing conditions.
Reduce the sewing speed.
Select a needle that is suitable for the
sewing conditions.
Adjust the tension and height of the
thread take-up spring.
Adjust the needle bar lift amount.
guide is not Adjust the position of the shuttle race
thread guide.
BAS-311G, BAS-326G
Remedy Reference
P. 89
Instruction
manual
P. 89
P. 90
Instruction
manual
Instruction
manual
P. 89
P. 92
P. 91
P. 91
Instruction
manual
P. 92
P. 91
P. 89
P. 89
P. 90
P. 91
P. 92