I will try a new thermostat and see how that goes. A simple analog heat only thermostat will be fine. Will any do? Or is there specific ones for 12V and 110V systems?
I will take a look and see if there is an obstruction as well.
When I was able to listen to the heater cycle I would hear a tick at the thermostat, 5 seconds later the fan would turn on, 10 seconds later I would hear what sounded like a flame igniting. Of course, each time it failed it was at night while sleeping or while we were away.
I will try and run it more when I can pay attention.