Help with dc motor and potentiometer! Thanks

OK so my dad has this old turntable and I got him some cool records for Christmas and I tested them out and it sounded good but now the motor isn't working, its kinda temperamental. I know the motor works because i tested it separately with a 9V, i guess the wiring is just kinda old and faulty. Any way my idea is to put the motor on its own independent circuit and adjust its speed with a potentiometer. Its one of those small DC motors 12V. I was thinking about hooking it up to a battery pack and a pot to adjust the rpm, I could mount the knob on the face of the player and adjust it until the music sounds just right. Then i could make a mark for 33 rpm and 45 rpm so he can change records with just a twist of the knob. Or slow them down and speed them up just for fun lol. How can I wire all this? I did some googling and tried with a couple pots and motors I've harvested over the years but all the pots seem to smoke and sizzle with only a 9V battery. Do I need a different pot? Please help! thanks  

Why not troubleshoot the actual problem with the turn table? The speed selector on the unit may be dirty or worn out. Its very unlikely the wire is faulty or worn out. Things like selector switches and pots on the unit will wear out well before any wiring becomes a problem.

If you really want to try and control the motor independently then you will need a motor controller. As you've seen a simple pot isn't going to do it.