It is usually the wiring, not the motor. Rodney is right, they are hard to kill. I have never had a really bad motor. Wiring on the other hand, is usually bad if the machine is 50 years or older. If it is hard and brittle, "crunchy" insulation, then get rid of the old wiring. DH routinely puts new wiring on my machines. We buy it by the roll. Better safe than sorry. Our local Home Depot has nice plugs too. He is losing his sight and has made diagrams for me to follow when he can no longer do it for me.