While you wait for answers, we may have found some information which could help you.
Click here for Timing Singer NeedleSinger 201 went bang , smelt and now won’t work?
the thread is bunching on underside of fabric it looks like birdnest?
Engine revving up ?
Need a service manual for a Singer Treadle Sewing Machine Model 66-1?
Singer 507?
Bobbin won't wind?