Get in touch with Colaw's Salvage. Quite a few years ago my furnace went out in the middle of the winter in Ohio. I got a used furnace within 2 days and when I looked it over before installing it had never been used. Call them and give them the make and model number of the one you have, they will get you a replacement on the way.
X2 on the advice to get a third electric heater, if you have 50 amp you can run 3 and that will do the trick. I am speaking from 4+ years of full timing.
You do need the furnace to be working when it gets real cold to put heat into the basement compartments.