[WildJohn]

Welllllll I checked all around here and only found some 3/4" check valves at the local home improvement stores and figured that by the time I adapted it to 1/2" it would be too long. The local RV dealer only had a plastic model and is 20 miles away.... I took it out to compare and found that the plunger was moving freely from the spring. looks like a retainer is missing... I put it back in without the check valve function functioning and made our shower much more functional until I can get a replacement to function...(DW said the first hot shower in three days felt PRETTY NICE and we won't discuss how long it was) I think part of the decision might have come from doing it at 10 degrees F. with a pretty good wind blowing.
I didn't even know there was an access panel in the pantry where I can reach it. I need to remove a few hundred pounds of staples from the pantry and look for it... can you give me a little more direction as to where it is.. I know where the one is behind the shower at near eye level.
Thanks everyone... this would have been a real head scratcher if it were not for this forum
John