While you wait for answers, we may have found some information which could help you.
Click here for Timing Singer MachineSinger 507?
how to get the tension right on my machine?
My CG 500/550 Singer Sewing Machine's bobbin isn't working?
Singer 201 went bang , smelt and now won’t work?
Need a service manual for a Singer Treadle Sewing Machine Model 66-1?
the thread is bunching on underside of fabric it looks like birdnest?