I too have been struggling a bit with focusing my 500CM. It's easy enough on a tripod but when I try to shoot hand-held, especially wide open I find that I'm often missing focus. I am positive my kit would immensely benefit from a good CLA, but I figure to get everything done it's going to cost around $500-ish from Mr. Odess (if I want everything done). I know that I would honestly prefer the Mamiya 7 as a system as I'm more of a RF person at heart anyways, but I literally couldn't say no to this 'blad for the deal I got.
I don't particularly want to get a Prism for it as I like how compact it is with the WLF, but is there a better screen to buy that isn't horrendously expensive? The one I have right now is a plain matte with a large central microprism dot. I think I would like it better if it were brighter, or perhaps I just need to stop shooting in such low-light conditions! Ha (I'll leave that to my Hexar AF)