Singer 500
I have a Singer 500 that works pretty good......except lately it has developed a bad habit!?!!? I'll be sewing along and then it will stop and knot up under the fabric. It has been serviced lately and I keep it cleaned and oiled. It also does it after I have stopped and then start again. It looks like the bottom thread is getting caught on something, but not sure what to look for. Sure would like some suggestion!!!!! Bette