Rare find!
The heating element area looks pretty clean. I have an early #25 and
it would not heat up at all. Open-circuit on the meter. After close
inspection the joints between the cartridge and plug wire looked hinky
so I cleaned the cartridge contacts and plug wire ends, put it back
together, and just like that it heated up as it should. A really dirty
engine but it cleaned up and runs nicely.
Good luck with your project. It will be very rewarding. And it has a
riveted boiler - very cool. I'd probably try it on air right away, and
if it runs and the heater is good try a steamup, even before cleaning.
Good Luck,
Wayne