Is it possible that the valve is reassembled correctly - but hoses are back on the wrong nipple?
I have a spare with all the hoses attached...can post a photo of it.
As for that little one-way valve....never had it apart.
So, does it seem that your tank can exhale, but cannot inhale?
Air moving into tank when you crack the cap after a hot sit? Or is it moving out of the tank?
Stig