Since it works fine on 33, I would check a few things about the 45 speed. 1. Do you have the problem with a 45 LP as well as a 7”? 2. There is a speed adjustment dial at the on the upper edge of the control square as well as a trimmer on the circuit board that you should try cleaning or at least moving back and forth several times. 3. I would check that the platter is not touching anywhere and moves freely up and down/l-r when a record is on. 4. The single likely culprit is the speed selector relay. Since 45 is rarely used, the contacts have been known to oxidize and the best approach is to replace the relay.