Can a digital system be applied to my RB67 Pro S camera?

If the problem is on the magazine's counter and if the spacing of frames is correct then the counter dial is loose. two screws on the outside front of the top of magazine, two screws in the film chamber hold the top cover. remove leather cover on winding lever loosen screw and remove. you can then remove the complete top housing to expose the counter mechanism.

Mamiya RB67 Pro SD that is new to me. loaded the film correctly took the first shot. But, the film won't advance. What am I doing wrong?

Have you tried it without the back attached, or without a dark slide in the back? Many cameras have an interlock preventing the shutter from firing while the slide is in. If that doesn't work, remove the lense and try it all over again - many times on these model's the problem lies in the lense, not in the body.

If neither works, consult a tech. But, expect more in repairs than you probably paid for the camera since these things are going for well under $300 these days.

Some of the gears are probably loose. I would suggest you take it to a professional camera shop.

http://stores.ebay.com/photobooksonline/Service-Repair-Manuals-/_i.html?_nkw=Mamiya+rb&submit=Search&LH_TitleDesc=1&_fsub=6&_sid=98011905

You might have an earlier rb pro S ( not pro sd ) version.
The later pro sd lenses have a larger diameter rear element.
The rb67prosd extension yube is clearly marked pro sd the older version just has-
mamiya no.1 45mm.

There is good chance that the back needs a spring replaced. I've seen them fail many times.

This is not the best solution as it indicates a faulty film back. The film should advance without resorting to activating the film-wind release lever. That is only for intentionally advancing a partially exposed roll of film. Make sure the multi-exposure lever is not engaged and that the counter does advance and the red mark disappears as you advance to an unexposed frame.

Solutions here....
http://www.apug.org/forums/forum51/16253-mamiya-rb67-lens-stuck.html

Start by making sure the dark slide is removed, the camera will not fire with it in place. The next step is to check the rotating back to make sure it is locked in either the vertical or horizontal position. Without film in the magazine, the multi-exp lever on the back must be set to show the red dot under the advance lever. You can check the camera without the back by removing the rotating back using the latch on the bottom of the camera