Thanks for the replies, all... sorry for the delayed update - I forgot all about this once it was fixed!
As Dave Garfield suggested, CALIBRATE did the trick and put everything in proper working order - but not before i'd spent some time disconnecting/reconnecting all wires and extracting/reseating all the socketed ICs. So the lessons i learned were: 1) the calibration routine doesn't just tune the oscs, it also puts other things in order; and 2) it's easier to run the calibration routine in 10 seconds than to take the synth apart in an hour looking for bad or dirty connections. End result: AWESOME! Just like i knew it would be. Thanks all!