We may have found other answers which could help you.
Click here for Sew Stiches SewingBobbin won't wind?
1965 Singer 275k sewing machine foot pedal?
the thread is bunching on underside of fabric it looks like birdnest?
Singer zigzag 457 Stylist not threading bobbin/making stitch?
how to get the tension right on my machine?
Singer 201 went bang , smelt and now won’t work?