Thanks for posting this CaptainLarry
As for the safety conscious out there. I do not hold CaptainLarry responsible for my actions. I do not recommend for anyone else to repair their valve. There is some potential for risk in servicing a gas valve yourself. If you attempt to repair your own gas valve you are assuming responsibility for your own actions.
I to had a leaking 25m19v valve and repaired mine after reading this I took it a few steps farther and disassembled my regulator too if you firmly pull on the center of the diaphragm the plunger will pull though the seat then the plunger will pull out of the diaphragm and the diaphragm will pull out of the metal disk assembly is opposite of disassembly it goes back together easier then is came apart
All the rubber parts looked and felt new so I went ahead and cleaned mine out with soap water, rubbing alcohol and a tooth brush and reassembled when it was totally clean and corrosion free
Mine too was full of corrosion but only in the valve section, the regulator half was corrosion free so that would leads me to believe the corrosion is caused by an external factor such as your suggestion of water getting in there when winterizing maybe though the outlet orifice, not the propane itself.
I also put a manual shut off valve inline with the solenoid valve so I can manually turn it off in case this repair dose not last but for now it is working correctly, I individually checked that the valves pickup and dropped out, there is no leaks from the valve half’s and no leak though the valve.
The valve was reassembled the way it was disassembled and all internals show no signs of age, ware, or damage other than some slight corrosion that is now clean.
