Quick take. this was a great repair project and it now produces up to 6 volts of power.
I received this engine a few weeks ago. The pressure gauge was N/G, the sightglass leaked, the generator wouldn't generate, and the heater would not work and registered as an open circuit.
So, I fixed the sightglass and generator to function as they should, replaced the bad pressure gauge with a plug, and finagled the heater back into working. If anyone has a reasonably priced original pressure gauge I'd love to buy it - or maybe trade for it.
As it tuns out someone, long ago, dribbled water down the side of the boiler and onto the heater. Bad engineering from the same folks who gave us modern rocketry - go figure. So, the exposed terminal wires shorted and melted a bit cutting the circuit. I was able to get the nichrome heater wires back to the current supplying wire (with asbestos insulation), formed a sort of loop, put the nichrome wires into it and pinched the loop shut to hold the wires in place. No solder. After it was all reassembled I noticed it was all a bit tight down there with exposed wiring near metal so I dropped in some mica sheets to act as a barrier and a sheet of insulation from Jensen to tighten it all up. Works for now.