If the solenoid is HOT and the jack retracts OK when manually opened, you just replace the valve. NEVER SWAP VALVES. THAT DESTROYS THE VARIOUS o RINGS ON THE VALVE. You never need to swap valves to diag a HWH problem. Swapping is done by inexperianced DIY people. You need the RAP0642 replacement. Doug
http://www.hwhcorp.com/mr60200h_e_sol.htmlPS, The reason that solenoid is HOT is because it has had 12 volt power longer than 10 minutes. It has power longer than 10 minutes because the system will not kill power to that solenoid until the offending jack has fully retracted and the red down light goes OFF.