5. TROUBLESHOOTING
110
5-12. Uneven seams (10) …… All stitches
Cause
Check
Remedy
Page
Upper thread threading
Thread the upper thread correctly.
Instruction
manual
Threading
Lower thread threading
Thread the lower thread correctly.
Instruction
manual
Thread path
Flaw or abrasion on the
thread path
Polish with buff or replace the part.
Especially, pay attention to finishing around needle
plate hole.
-
Needle installation
Insert needle fully into needle bar
Instruction
manual
Needle
Needle size
Replace needle with thicker one.
-
Thread chips or dust
Rotary hook rim
Rotary hook edge
Around needle plate hole
Remove thread chips or dust
-
Upper
thread
tension
Increase upper thread tension while checking
stitches.
Instruction
manual
Upper thread
Thread and needle
Replace needle with one that fits for the thread.
-
Flaw on the rotary hook
holder
Polish with buff or replace the part.
85
Rotary hook holder
Rotary hook holder and
inner rotary hook overlap
amount
Adjust the rotary hook holder and inner rotary hook
overlap amount.
85
Rotary hook
Rotary hook lubrication
Decrease the quantity of lubrication oil.
* Note that if you reduce the amount of oil too much,
thread breakages may occur.
102
Bobbin thread tension
Adjust the tension on the bobbin winder guide.
-
Bobbin winder guide
Uneven bobbin winding
Move bobbin winder tension bracket up and down to
adjust.
Instruction
manual
Lower thread
Lower thread tension
Adjust the lower thread tension.
Instruction
manual
Bobbin case
Damaged outside of
bobbin case and bent
bobbin holder spring, etc.
Polish with buff or replace the part.
* Use the HE-800A bobbin case.
-
Stitch patterns
Purl stitch, whip stitch
Set using parameter number 11.
Instruction
manual
3996Q
3997Q
Needle plate hole
Adjust the rotary hook
overlap amount.
Check flaw here
