One day I was going to use a couple small space heaters to put a load on the genset for exercise.  It didn't work.  The heaters wouldn't run on Fan, Low or High.  I tried everything I could think of.  The heaters would not come on.  I decided it was the transfer switch, took the cover off and started looking.  Dinner was soon, I left the coach and worried about all night. 
I went to the hardware store and got enough spare parts to wire around the faulty transfer switch so that I could get power to the motorhome.
Then I noticed that both heaters had their thermostats turned to zero.