We may have found other answers which could help you.
Click here for Sewing Singer Thread
the thread is bunching on underside of fabric it looks like birdnest?
My CG 500/550 Singer Sewing Machine's bobbin isn't working?
Singer 188K1 presser bar stuck?
Singer zigzag 457 Stylist not threading bobbin/making stitch?
Singer sewing machine 626 kno?
Bobbin won't wind?