Hi Neil
Yes, Nick rang me yesterday re the heater. As I said, I bought the machine off Spencer Davies in Eastbourne and I think he had it at least 2 maybe 3 years before me - so some time ago. Nick couldnt remember what heater he supplied (it was a few years ago and he has sold almost 300 scorpions in that time) but I must have jogged things and he found the details of "my" heater. He is now working to source for you no doubt.
I have not used any Prochem machine never mind your model, but I am 100% certain you WILL notice a difference in performance if used correctly.
By that I mean, using the right cleaning fluids for the circumstance, doing agitation, and dwell time if necessary. Agitation - I get really good results when I use my Envirodri.
To get the best from the heater, pour hot tap water in the clean tank (hot not boiling - too hot could be detrimental to the pump etc). Doing this helps the heater to get to a very good temperature.