I have an early 80's model Dou-therm furanace in a mobile home 2 wire hook up, No cooling. I don't thing there is a circut board. Furnace is clean and still in good shape. I got a Lux programable thermostat I just installed. It worked for a day and now the furnace won't fire up. The pilot is lit and I read 24 volts across the stat wires. I jumped the wires and still nothing. I'm getting my tools together. Is there a relay switch I should look for. And be able to possibly jump to test. There is power in and out of the transformer. Thanks for any words of wisdom.