Diaphragms can be replaced, but you will have to take it into a welding shop (and they may not even be able to get the spare parts, as it is a relatively old regulator). It may cost more to replace the diaphragm (after parts + service costs) than to just buy another one off eBayHuh, I got it for cheap last night on a bid which was immediately accepted. I should have waited for your response.
I'll keep reading up but can the diaphragm be replaced at all and for a reasonable cost or does it not pay? I probably should have waited to find a Victor somewhere but what did I know... live and learn.
Thanks for the info, your comments back on the old CO2 thread are a big help too.