Does anyone have a schematic for the circuit board for this? I am thinking possibly a stuck electromechanical relay on the circuit board. If so email it to me at [email protected].

You can tap on the relays (in plastic boxes on board) and if one is stuck it may come unstuck. The contacts are welded together now. The relays are very easy to replace. Just match them and solder in a replacement. Keep the same coil voltage and go for a higher contact rating, or wire in another relay to take the amperage by using the output to drive only the coil on a relay after you get it unstuck. You can buy a higher amperage relay at any HVAC store. Using a small contacter or fan relay would be perfect and since you are only using the circuit board for control voltage it would last for about 30 years.