We may have found other answers which could help you.
Click here for Sewing Machine Singer Stitch Length
Singer 507?
What size needles can I use for my Singer 39a3?
the thread is bunching on underside of fabric it looks like birdnest?
Bobbin won't wind?
Singer 188K1 presser bar stuck?
Singer zigzag 457 Stylist not threading bobbin/making stitch?