Don't want to bring a dead horse back to life but I recently rebuilt my Ranco valve in my 58 Harrison heater (Tom Myers - very nice unit). The capillary tube in this unit actually activates a small piston when heat is applied to the tube and coil (I used a heat gun) and it shuts the valve.
Rebuilding was pretty easy thanks to FRED getting me a new seal.
I followed the instructions at the Stude site and made a little anvil for pegging down the brass valve tabs. Worked well.
Piston closed Piston opening with heat Ready to roll - bead blasted, core pressure tested, new elbow hose, etc.. 
