We may have found other answers which could help you.
Click here for Sewing Machine Tension Singer
Bobbin won't wind?
the thread is bunching on underside of fabric it looks like birdnest?
1965 Singer 275k sewing machine foot pedal?
Singer 507?
Singer 201 went bang , smelt and now won’t work?
Singer zigzag 457 Stylist not threading bobbin/making stitch?