How do I fix it when the bobbin thread won't rise?

SOURCE: a horrible tangle

This is a bit late, could the bobbin case not be seated properly? You need to put it into place and then turn it clockwise until it seats soundly in the opening. Also, check for burrs...the needle may have left a rough mark on the plastic or metal in the bobbin area. A piece of batting, or even an old knee hi should snag on any rough areas.

SOURCE: Upper thread wraps around bobbin mechanism, while sewing

IT PROBABLY IS THREADED INCORRECTLY. GO SLOWLY BY THE DIAPHRAGM AND MAKE SURE IT IS THREADED CORRECTLY. ALSO MAKE SURE SPOOL PIN HOLDERS ARE IN PLACE THAT HELPS TO GUIDE THE THREAD CORRECTLY.

SOURCE: singer quantum sewing machine won't pick up bobbin thread

Try changing your needle

SOURCE: raising bobbin thread

These machines are timed by belt and go out of time a lot. Check and see that when the needle passes through the plate and travels upward 1/8" at this point the rotating hook should be right behind and above the eye in the needle,my guess is that it is out probably 1 tooth on the timing belt and can usually be corrected by removing the bobbin case and holding the rotating hookk with on ehand and forcing the handwheel with the other hand which will cause the belt to jump a cog and should put your machine back in time I hope this helps

SOURCE: Touch & Sew zig-zag model 758 - bobbin thread

email me for retiming instructions and remind me of your make, [email protected]