If it’s a belt-drive, a new belt may fix it right up. If it’s an idler wheel drive, very lightly sanding around the edge of the rubber idler wheel removes a hard, slippery glaze that very often forms and causes slippage, low torque and slow speed like a loose belt would. You need to remove the platter to get to the belt or idler wheel. You may need to remove a C-clip that keeps the platter from being lifted

If it’s a table with a DC motor and electronic speed control, there are usually PC board mounted controls inside to fine-tune the speed of the 33 and 45 settings using a small screwdriver.

You can print strobe discs here to set the speed perfectly if turns out your table can be adjusted…

http://www.vinylengine.com/strobe-discs.shtml

Good luck! I may be able to help more if you can tell me more about the table or take some photos… Feel free to message me.