@crusher and @edgunwest, thanks for chiming in on this issue. As I said in the OP, the look of the fitting's top/end seems off to me but I have no experience with such things. I just thought the valve inlet should be regular in its surface; as my photos show, my fitting is anything but. Polishing it down (very, very carefully) to get a smoother surface is something I am confident I can do. Reading elsewhere recommends cleaning off the black crud (no other term fits) that coats the grooves on the reservoir side of the fitting and using Teflon tape to seal the fitting. Again, all done very, very carefully so as to avoid damaging the grooves and not impeding the valve with excess tape on the reservoir side. On one hand, I'm frustrated to have to do all this so I can shoot a gun that I've been working to own for a year now. On the other hand, this situation will give me a great deal more confidence in maintaining my gun and pump down the road. On the whole, I'd rather gain the hard-won experience and be that much more capable as a gun owner and mentor to anyone coming up behind me. But it sucks to go another day without that sweet ping in my ear and smack from downrange.