I know it's an old thread but as I started it, I might as well finish!
I found that Warco stock these as spares for their own machines. A phone call had them in my hands a day later.
As Jez mentioned, there was a problem in trying to remove the retaining pins. I was able to wedge something into the end of the pin and with the aid of lots of WD40 and wiggling, they eventually came out. All sorted now, and I can stop worrying about one of the cams splitting in use!