Replying to Nifty Fifty choppy focus ring?

What's up guys, I bought a used 50mm a few days ago from here, and it seems to have arrived with a problem with the focus ring. It wasn't mentioned in the ad or anything, and I'm not sure what it is.

Basically, in manual focus, there are 3 spots in the range where there seems to be something blocking the movement of the ring. The ring can move past whatever is blocking it, but it makes the focus jumpy and impossible to smoothly pull. There's no problem with the autofocus though. Any insight?