We may have found other answers which could help you.
Click here for Needle Lower Thread
the thread is bunching on underside of fabric it looks like birdnest?
Singer zigzag 457 Stylist not threading bobbin/making stitch?
Engine revving up ?
Singer 188K1 presser bar stuck?
What size needles can I use for my Singer 39a3?
1965 Singer 275k sewing machine foot pedal?