Originally Posted by
Rosyhf
You didn't say what type of machine, if it's not computerized, take out the bobbin and thne unclip the area where the race hook is, take that out and clean any threads dust etc. replace everything.
Make sure that the small wheel on the big hand wheel is tight. Oil the machine, oil and clean the needle arm, that could be frozen because of dust.
I'm not sure what the race hook is. I'm using a Singer Touch and Sew (model 758) with drop in bobbin. The only way to wind a bobbin is to rethread with the bobbin thread. I clean out the bobbin area after each bobbin, although I did search a little deeper and found some more lint.
When it seizes, the top thread is only part way around the bobbin. If it's really bad, the top thread has bent the curved metal piece on the bottom right (at the front of the sewing machine), and the bobbin casing (? what holds the bobbin in place) has swiveled. I've pointed this out to the service guy the last three times it's been in for service, and he's never replaced that piece.