Uneven Seams (10) - Brother HE-800B Service Manual

11. TROUBLESHOOTING
11-12. Uneven seams (10) ...... All stitches
Items with a "*" in the "Page" column should only be handled by a qualified technician.
Cause
Threading
Thread path
Needle
Thread chips or dust
Upper thread
Rotary hook holder
Rotary hook
Bobbin winder tension
bracket
Lower thread
Bobbin case
Stitch patterns
155
Check
Upper thread threading
Lower thread threading
Flaw or abrasion on the
thread path
Needle installation
Needle size
Rotary hook rim
Rotary hook edge
Around needle plate hole
Upper thread tension
Thread and needle
Flaw on the rotary hook
holder
Rotary hook holder and
inner rotary hook overlap
amount
Rotary hook lubrication
Bobbin thread tension
Uneven bobbin winding
Lower thread tension
Damaged outside
bobbin case and bent
bobbin holder spring, etc.
Purl stitch, whip stitch
Thread the upper thread correctly.
Thread the lower thread correctly.
Polish with buff or replace the part.
Especially, pay attention to finishing around needle
plate hole.
Insert needle fully into needle bar.
Replace needle with thicker one.
Remove thread chips or dust.
Increase upper thread tension while checking stitches.
Replace needle with one that fits for the thread.
Polish with buff or replace the part.
Adjust the rotary hook holder and inner rotary hook
overlap amount.
Decrease the quantity of lubrication oil.
* Note that if you reduce the amount of oil too much,
thread breakages may occur.
Use the tension nut to adjust the lower thread winding
tension.
Move bobbin winder tension bracket up and down to
adjust.
Adjust the lower thread tension.
of Polish with buff or replace the part.
* Use the HE-800B bobbin case.
Set using parameter number 53.
HE-800B
Remedy
Needle plate hole
Check flaw here
Adjust the rotary hook
overlap amount.
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