If the motor is indeed "off" you would have to replace it. It might just be the capacitor has drifted. You can remove the metal motor housing underneath the plinth to get to it. I can't remember what value it is, but it's a common one. I would get a higher quality cap, if you're going to replace it anyway.
The new belt will help also. Make sure you clean very well, the pulley and the outer platter where the belt travels.
Also, I would clean out the bearing well and relube the bearing well and bearing.
The new belt will help also. Make sure you clean very well, the pulley and the outer platter where the belt travels.
Also, I would clean out the bearing well and relube the bearing well and bearing.