Direct drive spinning to fast

You don't say if it's a belt or direct drive turntable. If it's a belt then something might have caused the belt to slip off it's normal position so it runs fast.
Direct drives are more complicated, but it would seem that the voltage control circuit that feeds the motor is applying to much to it and the therefore is faulty.

Clearly an electrical fault. Could be something to do with the power supply or the speed control circuit, or even the motor itself.
For the manual visit the Gemini website.

A lot of turntables have two belt positions on each pulley. One for 33 and one for 45. I would check to make sure the belt hasn't slipped into the 45 position.

Direct Drive turntable's have electronically controlled motors with complicated systems to keep them at the right speed.
My guess is that there could be a power supply issue that feeds one of the motors that is sending a much higher voltage to it. But that's just a guess. You might want to look around for the service manual for it to see how the motor is controlled.

Hello!
are you sure, that your speed selector is on 33.3rpm, not 45?
assume, it's in correct speed settings. do you know, that across the ocean power grid AC frequency is 50hz, in US it's 60hz. Means: ac motor will spin faster, than it should. If you bought this unit abroad, that's where is your problem at. some expensive units have 50/60hz pulleys switch, some not. Especially, if it's DC or direct drive motor. Check your owner's manual for specifications. May be you find an answer. If not, there is a problem with motor's regulator, which is built in(DC motor). Turntable is a belt driven. If you won't find 50/60hz adjustments, take it to repair shop.
Good luck,
Alex.

is this direct drive or belt drive?i have a tchnics 1200 mk 11

I don't know the answer, but you have written one of the finest, most comprehensive problem descriptions I have come across. In mechanical scenarios, that is priceless. I'm sure a turntable guru will see it and go, "aw. I know what that is". Good Luck.

It seems something may have come loose over time or history, but you will have to delve inside to see what it is. It sounds as though the fault should be obvious.

If you do not want to do this, a repair shop should have no problem. I assume that the deck is working ok otherwise.

Turn the tturntable over, there is a speed control pot on the bottom

If it is a direct drive TT then it uses some electronic circuitry to control speed and it sounds like that circuit is having a problem. Possibly the actual driver IC for the TT motor has gone bad. Good luck.