We may have found other answers which could help you.
Click here for Sewing Machine Stitches Repair
the thread is bunching on underside of fabric it looks like birdnest?
1965 Singer 275k sewing machine foot pedal?
Singer 188K1 presser bar stuck?
Singer 201 went bang , smelt and now won’t work?
Need a service manual for a Singer Treadle Sewing Machine Model 66-1?
Bobbin won't wind?