My Singer 500 is having problems
 

I've been sewing on this 500 for 50 yrs and it has not failed me. BUT now there is a problem that I can't seem to figure out. I'll be sewing along and then it will just stop and knot up underneath. the thread is catching on something, put I can't figure out what it could be. It's pulling the top thread down. I'm hoping someone on this great board can give me some ideas as to what it could be........

Have you changed the needle recently?

Have you checked the bobbin is wound evenly/threaded correctly?

Have you cleaned any lint out from under the feed dogs?

These are the first things I would check if my machine was doing this. If none of these made a difference, I'd check to see if the tension assembly has some lint or dirt in it.

Thank you, I've done all those things and also oiled the machine. I've cleaned the tension, too. When the machine stops, I have to wiggle the thread and sometimes pull it to get it loose from underneath. It sure has me stumped.

Is there a hairline crack in your needle plate? Also check your thread path. After 50 years a guide may be worn thin and cause a problem, same for the bobbin area look for unusual wear and compacted lint in the bobbin case. There is a groove on the inside of the bobbin case - near the top - that over time gets filled with lint and dirt. remove the case from the machine and using some alcohol and a toothpick, clean out the groove. While you have the case out clean out any dust bunnies and put a drop of oil on the hook.

Thanks, will check those things. It does help to put some oil on the hook....

My wife's Singer 500 was purchased in 1961 and she stated that this has never happened to her while sewing. It has happened when starting if she does not hold the threads. She also mentioned to check the entire thread path, top and bottom and try another bobbin. This will happen if a bobbin is wound to loose or to full. . If her 500 acts strange in any way she performs the complete maintenance that was shown her when she purchased the machine.

Thanks everyone, I took some emery cloth to the needle plate and also the thread path. There must have been something there, as it isn't doing it now. Thanks so much, I knew you folks would have some ideas!!!!