Sounds like the motor control circuitry has a fault, beyond the effects of maintenance adjustments. Quite often, a transistor and perhaps other active electronic components are used to provide a stable calibrated voltage that drives the platter motor. If one of these components fails, the drive motor can be fed the larger unregulated supply voltage; hence, the out of control platter speed. This can happen to belt drive or direct drive turntables. Not so with the old rim drive units. Unless you have technical experience in this area, you should have a stereo type tech look at it. I'd avoid the high end audiophile type repair services. Shop around for an old school regular tech, and the repair should be relatively inexpensive. FYI, I've seen these hi end shops charge $50 or $60 for a turntable belt that should only cost around $20. If you feel the repair estimate is too much, you can find good used turntables at some stereo stores, or even at some thrift shops for a fraction of replacement cost. Depends on your standards.