I was not getting gas flow to the burner of the Suburban gas water heater. The gas valve has two solenoid valves for redundancy; if one fails open the other will prevent gas flowing. The solenoids had continuity and clicked when power was applied but no gas. So it looked like at least one solenoid valve was stuck shut. I replaced the gas valve and the heater works fine now.
I took the old gas valve apart and found significant rust and corrosion in the last solenoid valve chamber that feeds the line to the burner. The other solenoid valve chamber looked fine. About a year ago I had noticed water in the line below the gas valve when I cleaned the burner.
The biggest concern is that if the one solenoid valve fails open or gets debris under it then that leaves only the other solenoid valve to prevent gas from flowing. Is it typical for there to be water in propane that can cause corrosion in the gas valve?