[brwill2005]

Maybe you have found the reason the person sold it. Is it still under warranty? What model do you have? I am looking at the insruction booklet for the PE12-175. Sounds as if the overheat protection is some type of complicated electronics. Maybe there is a malfunction with that system that is not visible. It also says if the on-load speed is reduced or the electronic signal indicator lights up, to run the machine at idle until it turns off.