Good Morning from Brooklyn...
Sorry to hear of your burned out heater. Both my Empire B43 and 43 suffered
this fate. I went with cartridge heaters as a solution. I had 200watt heaters
laying around, so I used them. A bit weak, but they both will run fast enough
satisfy me, especially after a fix.
The 90 is a nice and simple engine. You can drill a hole in the boiler and
use a cartridge heater - it has been done often enough. Instead of drilling a
hole the boiler, I would try and nestle it just below the boiler. Try to get
a heater of 300 watts. When you place it up against the boiler add a couple
of iron (steel) pieces up against the heater on either side so so as to help
the heater dissipate the heat. You could also wrap the heater in a moderate
guage baling wire to do the same. If you don't do either the naked cartridge
will overheat, burn and go...incandescent. Been there/done that. Or, try the
Jensen heater solution.
I've added a video link to my 90 running. It's a bit tricky to adjust the
trunnion spring, but you'll get it going.
Good Luck,
Wayne
Wayne