I believe you are correct all around, should be N.C. if no 12V.
You can check vavle by shutting off propane @ tank, IIWMI'd run propane out by burning it off @ stove burner, remove valve, & blow thru it. If you can blow thru it w/no 12V it needs to be replaced. Note that replacing propane fittings requires a propane listed sealant. You can get yellow gas-resistant teflon tape, but I recommend the gooey yellow stuff in the small tube as you get a more bullet proof seal 1st time.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project