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11. TROUBLESHOOTING
Problem
Possible cause
Page
à
7. Lower thread is tangled at
9 Is the bobbin spinning direction correct when the lower thread is
the sewing start.
being pulled?
Set the bobbin so that it turns in the opposite direction to the rotary
hook.
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E
* is there too much thread wound onto the bobbin?
Ee
The bobbin winding amount should not be more than 80%.
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ee,
à
9 Is the free spinning prevention spring attached?
Attach the free spinning prevention spring.
-
wer
thread
® Is the bobbin turning smoothly?
If the bobbin is not turning smoothly, replace the bobbin.
-
* Is a bobbin other than the light-alloy bobbins specified by Brother
being used?
Spinning of bobbin
Use only bobbins which are specified by Brother.
-
during thread trimming
8. Upper and lower threads
e Is the needle bent or is the needle tip broken?
are breaking.
Replace the needle if it is bent or broken.
-
* |s the needle properly installed?
If it is incorrect, install the needle correctly.
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* Is the needle properly threaded?
OA
If it is incorrect, thread the needle correctly.
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WC
© Is the upper or lower thread tension too weak or too strong?
Adjust the upper thread or lower thread tension.
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CUL
e Is the upper thread may be loose because the thread tension spring
LANE
operating range is too small?
ts
Adjust the position of the thread tension spring.
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ares
|) | mr
è Is the rotary hook or other part damaged?
If they are damaged, smooth them with an oiled grindstone or re-
place the damaged parts.
-
9. Incorrect thread trimming
è Is the fixed knife or movable knife damaged or worn?
(upper and lower threads
Replace the fixed knife or the movable knife.
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are both not being
trimmed).
10. Incorrect thread trimming
| ® Is the needle properly installed?
(upper thread or lower
If it is incorrect, install the needle correctly.
24
Se
e Is the fixed knife or movable knife blunt?
trimmed).
Replace the fixed knife or the movable knife.
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DB3-B775, B776
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