those motors are supposed to spin free. if this is a rebuilt motor you may find the distance from the end bells to the shoulders on the rotor a little - slightly larger. you may get away with it by filing down both oil-lite bearings a touch so the rotor is centered in its field. one end of the motor has a four bladed fan on it the other side terminates in an air compressor. 3.5 psi is maximum for this compressor to produce. the air is directed to the nozzle which acts as a venturi to suck the fuel out of the tank and atomize it through the nozzle.