Topic: RTS II with "unsmooth" film advance. How to fix?

I hope to pick a brain or two. I have a Contax RTS II, that is functioning normally, apart from the fact that winding is a bit gritty and "ratchetty". I would expect this to go much smoother in this model. Is there a way to fix this? Is there bits in there that need lubrication?

I appreciate all the pointers I can get..

Thanks

CZ 18 28 50 85 135  MD 28 35 50 85 135 Rollei SL66 80 150 250  RTSIII Aria(2x) X700 X300