Quoted from TheJerol:Problem solved!
Turns out all you have to do to have your technical questions INSTANTLY answered -- BY PHONE -- is buy a machine from HEP. Evidently, he's kind of like Pinball Santa -- he knows when you've been posting, he knows when you're in need. He saw my post, called me and now it's working.
The problem, by the way -- expertly NOT shown in my photos -- was a loose ribbon connector between the driver board and the MPU. Plugged in and we're good to go.
Thanks for all the rapid replies -- this community never ceases to amaze me!
Mike
Awesome! How good did that first game feel after the panic subsided?!