Turntable slows down then back up to speed.

My record player turntable slows down and then goes back up to speed. It started doing this after our cat (we think) knocked the arm off its rest which caused the turntable to constantly run for a couple days before we noticed. Now when we play an album it slows down, speeds back up and sounds warbled. Dont know if it is the platter motor or the belt. Which do you think it is?