2
Condition Cause How to Fix Reference
3. Breaking
upper
thread.
1. Initial sewing speed is
toofast.
2. Threadpathisincorrect.
3. Needleisbentordull.
4. Toptensionistoostrong.
5. Needlesizeisinappropriatefor
fabric.
6. Needleeyeisworn.
7. Needleholeinneedle
plate is
wornorburred.
Startwithmediumspeed.
Usetheproperthreadpath.
Replacewithanewneedle.
Adjusttoptensioncorrectly.
Useappropriateneedleforfabricand
threadinuse.
Changetheneedle.
Repairtheholeorreplacetheneedle
plate.
4. Breaking
bobbin
thread.
1.Bobbinholderisincorrectly
threaded.
2.Toomuchthreadiswound
onthebobbin.
3.Lintisstuckinsidethebobbin
holder.
4.Threadqualityistoolow.
5.Threadisjammingaroundthe
bobbinholder.
Setthebobbinthreadcorrectly.
Adjustthepositionofbobbinwinder
stopper.
Cleanthebobbinholder.
Changetoahighqualitysewingthread.
Clearoutthejammingthread.
5. Needle
breaks
1.Needleishittingtheneedleplate.
2.Needleisbentorworn.
3.Needleishittingthehook.
4.Fabricisbeingpulledtoostrongly
whilesewing.
Seemechanicaladjustment“Needledrop
position”.
Changetheneedle.
Seemechanicaladjustment“Clearance
betweenneedleandtipoftherotary
hook”.
Guidethefabricgentlywhilesewing.
P. 9
P. 12