Okay... all seems well. Problem figured out and remediated...
"Old style" compression fittings seem to involve just splaying out the tube and nuzzling it up against the conical receiver.
More recent style seems to involve folding over the splayed out tube and making almost a 2-layer ending... which bottoms out easily on an old-style conical receiver (or at least... THIS one did)
Rummaging around in those old peanut cans in the garage produced a new style tube to go with the new-style cone that was on the pump...
No leaks, runs smooth...
