So I acquired a OLD 1/4 hp 120v motor. I cleaned it up some and kicked it on. It spins but after a few min of running the motor was getting really warm. I notice that when i was cleaning it out some dirt came out of vent holes that are located below the shaft on the front and back of the motor. It doesnt make any noises (other than a hum when running) and the drive shaft seems to spin pretty freely. Is it normal for a very old motor to get really warm while running with no load?