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Checking the rotary hook for nicks and scratches
If you are having problems with thread breaking or fraying on all the needles on a
particular head, if multi head machine, then you might have a bad presser foot or it needs
the height adjusted. If changing the presser foot and or height does not fix the problem
than the rotary hook might have some nicks or scratches on it. This is one of the most
common problems and should be checked before adjusting the rotary hook timing. Nicks
and scratches on the rotary hook can be caused by needle breaks and or being careless
when you remove a bird's nest, i.e. using the tweezers to pull and pry the thread out from
underneath the needle plate.
1. Turn the rotary hook, by either turning the pulley in the back on a 1 and 3 head or
rotating it by hand if on a 4 and 6 head, so that you can inspect the thread slide
face for nicks or scratches (see diagram below).
2. Feel along the thread slide face to see if it is smooth, free of scratches and nicks.
If you feel any and they aren't real deep. You might be able to sand or polish the
area until it is smooth. 600 grit sandpaper works well for this. Anything rougher
will result in a finish that is not smooth enough for the machine to operate without
breaking the thread. Extra fine crocus cloth after the 600-grit sandpaper works
well to polish the surface to chrome like finish just like when it was new. Any real
deep gouge or nick you probably won't be able to sand out so the only option is to
replace the rotary hook.
3. After checking and repairing the rotary hook it will need to go back to it's normal
position. This can be done by either turning the pulley in the back on a 1 and 3
head back to 100 degrees or by pressing the back switch on the head on a 4 and 6