I do have a problem with your finding... The burner section is supposed to be isolated from the inside of the pup. If your valve is wide (and no ignition happened) open no gas should flow to the inside of the pup except for when it goes out in the atmosphere and could be pushed back in via a window. In other words, if your valve is stuck open you should not smell propane. Having said that, I don't mean than that valve is not defective, you just proved it wrong BUT you might have something else.... Let us know what you find after you replace the valve.