And I did almost nothing. I blew the dust out of the thermostat with canned air, and cycled the control through its entire range several times, INCLUDING past the clicky "ON-OFF" detent several times.
Then I set it at 72*, and a few minutes later I heard the popping of expanding metal, and the smell of a long-dormant heater coming back on duty. I'd vacuumed out the baseboard unit just in case it had any stinky stuff in it, but it looked pretty clean.
It took about half an hour, but the wall thermometer stabilized at 73*~74* for the next several hours, so it looks like the heater is functional again.
The only thing I can think of was that cycling through the power ON-OFF detent several times cleaned the contacts enough to wake up whatever dimbulb controller is in use. Most late 1970's home thermostats were quite crude, so it has a very simple mechanism.
I'll have to try and find a model number on the Chromalox thermostat so I can learn more about them.
Anyway, we now have heat in every room, and we'll avoid the dreaded "one cold room" issue that I've read can cause problems with condensation.
Headed up to see the kids on Sunday, and drag back another load of stuff. If the relatives are around, I'd suspect we could get all of it out of there. The last time we pulled more than half out, so this time should be a bit easier.