We may have found other answers which could help you.
Click here for Thread Sewing Machine
Singer zigzag 457 Stylist not threading bobbin/making stitch?
Presser foot is loose?
Singer 188K1 presser bar stuck?
the thread is bunching on underside of fabric it looks like birdnest?
Need a service manual for a Singer Treadle Sewing Machine Model 66-1?
Bobbin won't wind?