We may have found other answers which could help you.
Click here for Sewing Machine Bobbin MechanismWhat size needles can I use for my Singer 39a3?
1965 Singer 275k sewing machine foot pedal?
how to get the tension right on my machine?
Presser foot is loose?
Singer 201 went bang , smelt and now won’t work?
Singer zigzag 457 Stylist not threading bobbin/making stitch?