Thanks heaps for the input guys. I hadn't considered a chemical, but its certainly a real possibility, probably more likely than it melting itself with a constant, too high a current.
OK - so it looks like the ball is now in my court. Time to start disassembling the little fella and see what's what, and make a list of parts required.
I need to head out to Central Australia for a couple of weeks work in a few days, so the disassembly will be one of my jobs when I get back.
Again, thanks for the help, and I'll send more photos as the project progresses. I've worked on lots of Stationary Engines before - but never an Ohlsson and Rice - so I'd really value your collective thoughts.
Polybus got a reaction from Wallfish in Amp Champ generator