Hi I have a Hasselblad H1 the highlights are suddenly "crazed" any idea what could be causing this?

One possible source: http://www.ebay.com/sch/i.html?_kw=Hasselblad+500mm+f8+CF+Lens

Send to a repair facility like CRIS or United camera repair. This is something mechanical that cannot be repaired at home.

http://butkus.org/chinon/hasselblad/hasselblad_503cw/hasselblad_503cw.htm

This is an $18,000 camera. You shouldn't be asking us for advice...you should be contacting Hasselblad!

http://www.butkus.org/chinon/hasselblad.htm
Get the manual. They are picky, it might require the shutter to be wound or something like that.

The Hasselblad ELM does not need adapting to use the Imacon or hasselblad digital back  the following backs fit on the ELM and can be triggered with a cable that should be supplied with the back. 
Hasselblad V96c 16mp square format back  Hasselblad CFV 16mp square format back with CF slot Hasselblad CFVII 16mp square format back with CF slot + larger screen
the following backs will work but need to have a V adapter plate fitted to the back 
96c 16mp square format back  132c 22mp 645 format back  528c 22mp 645 format back with Multishot option CF-22 22mp 645 format back with CF slot CF-22 MS 22mp 645 format back with CF slot & Multishot option CF-39 39mp 645 format back with CF slot CF-39 MS 39mp 645 format back with CF slot & Multishot option

When fitting and digital back to an older camera the best advice is to get the camera body serviced to ensure that the back mount is correct as the digital backs require a better fit than the film backs did. If the mount is off it will cause back or front focus. 

This site has a link to downloading the manual:

http://www.butkus.org/chinon/hasselblad/hasselblad_503cw/hasselblad_503cw.htm

Those speeds tend to hang up from lack of use. You can try exercising them by cycling through the speeds, but it will most likely need service. The lubrication on the gear train has probably dried up, it is a common problem since those speeds aren't normally used.

There were several versions of the 500C/M as production was over many years. The 501C had all the latest revisions of the 500 C/M series to make it the better choice. You'll get more $ for the 501 for this reason. Later versions of the 500C/M had a much better coil spring to control the mirror for starters. Unless you are going to use this camera for daily professional use, either would be a reliable camera. A good way to check the amount of use on any Hasselblad is to look at the back of the camera where the film magazine mounts. A good solid black with no shiny spots on the plate would indicate little use. There are raised lines around the aux. shutter opening that will wear as film back are removed and replaced.

you ****