Brother S-7100A-403 Instruction Manual page 46

Problem
8 Material slippage
9 Lower thread is tangled at
the sewing start.
Spinning of bobbin during
thread trimming
Lower
thread
10 Upper and lower threads
are breaking.
11 Incorrect thread trimming
(Upper and lower threads
are both not being
trimmed)
12 Incorrect thread trimming
(Upper thread or lower
thread is not being
trimmed)
・ Is the presser foot pressure too strong?
Adjust the presser foot pressure.
0750M
・ Is the bobbin spinning direction correct when the lower thread is
being pulled?
Set the bobbin so that it turns in the opposite direction to the
rotary hook.
・ Is there too much thread
wound onto the bobbin?
The bobbin
amount should not be
more than 80 %.
・ Is the anti-spin spring attached?
Attach the anti-spin spring.
・ Is the bobbin turning smoothly?
If the bobbin is not turning smoothly, replace the bobbin.
・ Is a bobbin other that the light-alloy bobbins specified by Brother
being used?
Use only bobbins which are specified by Brother.
0751M
・ Is the needle bent or is the needle tip broken?
Replace the needle if it is bent or broken.
・ Is the needle properly installed?
If it is incorrect, install the needle correctly.
・ Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
・ Is the upper or lower thread tension too weak or too strong?
Adjust the upper thread or lower thread tension.
・ Is the upper thread may be loose because the thread take-up spring
operating range is too small?
Adjust the position of the thread take-up spring.
・ Is the rotary hook, feed dog or other part damaged?
If they are damaged, smooth them with an oiled grindstone or
replace the damaged parts.
・ Is the thread path damaged?
If the thread path is damaged, smooth it with sandpaper or
replace the damaged part.
0471M
・ Is the fixed knife or movable knife damaged or worn?
Replace the fixed knife or the movable knife.
・ Is the needle properly installed?
If it is incorrect, install the needle correctly.
・ Is the fixed knife or movable knife blunt?
Replace the fixed knife or the movable knife.
Possible cause
winding
S-7100A
8. TROUBLESHOOTING
Page
2124M
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