Thanks for the reply.
I took apart the coupler and inspected the rubbery check valve contained within. It was certainly moist with beer…on all sides. There’s also a broken piece of plastic off the check ball retainer (part #1) on the top of the thing. Thinking “the heck with it,” I just got back from my local homebrew shop with a new coupler and an independent in-line check valve kind of like this one only each side has a barbed end.
http://www.micromatic.com/draft-keg-...d-1600CAB.html
I just hooked everything up and am patiently waiting (actually, I had to get back to the office) for the beer to properly re-carbonate. I’ll report more this evening, after I’ve had a chance to pour a few.