I have a Turbo aire high velocity fan. It was have trouble getting going. So I took the motor out and got oil down the litttle hole on the back of the bushing /bearing. But the shaft end had no hole so i took an insulin syringe and got a bit of oil down around the rubber washer . All good for one or two days and it got slowed up to start. So i repeated the same with oil and release oil mixture. All good agian for a few days. It seems that the oil is not lubing the shaft or is going stick. the fan turns real slow and evetually goed gull speed. After I oiled it I could manually spin it like nothing.