Thorens TD 165 Speed & Belt Setup Questions

A number of years ago I bought fa TD165 for my daughter from a friend who restored it, adding better cables, a Jelco arm and Audiopoints. Now she has a new table and I'm readying the Thorens for sale. 

I tested speed with my KAB strobe. 45 looks great, but at 33 it's running a bit fast. A google search found a couple of comments suggesting there's a threaded post that can be used to dial in speed. Others replied that it was for pulley tension and not really a speed adjustment, even though it does have a bit of impact on speed. 

So my questions are:
1) If the belt is worn and needs replacement wouldn't both speeds be off? 
2) There's a tiny bit of black gunk on the lower area of the motor pulley, probably rubber residue from the belt usually being set to 33. Would cleaning the post with alcohol, etc. remove the gunk and perhaps result in a slightly slower speed at 33? 
3) Would you recommend adjusting that rod setting to attempt to slow down the 33 speed? Does adjusting the rod setting while playing at each speed adjust the speed independently or would it affect both 33 & 45?

It's a really nice vintage table! I want to get it tip-top before it finds a new home. Cheers,
Spencer