Hi Nigel,
If I had any issues with my 500c/m or any of my lenses, I'd have no problem taking them to Aperture on Museum Street from whence most of it originated. Richard and Patrick have always played fair with me and I've yet to find anyone who has a bad word to say about them. If they aren't confident to fix the problem, they'd send to Hasselblad who, from all accounts, are able to service most kit from the V series.
The downside, I suppose, is that as it's not cheap kit, servicing / repairs won't be cheap either. But it is superbly made and the lenses are beautiful.....