Stewart,
It depends on which Hasselblad body you are in trouble with. The regular 'C' bodies can be done by a number of techy's but you will need to flush them out by asking local dealers. If you are talking about any of the focal plane shutter bodies, it MUST go initially to CR Kennedy. They will send it first to New Zealand (that is where their service dept. is now!). Failing that, it is returned to Sweden.
I used to have a good contact at Kennedy's service dept but he is retired now. I would certainly talk to them as a starter. Whatever, you probably going to have to send it somewhere interstae, or O.S. Expect a minimum turnaround of 1 week, pending the nature of the problem.
My 203FE ended up dead after 12 years service and they could not fix it, even at the factory. They gave me a new one..... NOCHARGE. True.
Good luck.