What is the 'stuff' ,that you are calling frayed, made of? Is it wire or a sort of fabric? IF it's wire --- DO NOT PLUG this machine in again until a professional looks it over. If it feels like a fabric/wrapping material,( test/feel it while UNPLUGGED ) it isn't the source of your problem. Doesn't sound like the foot pedal either, I'd vote on the brushes like I said before.