At the space Thursday evening 3/8 I hauled the display out to see if I could address what looked like lack of +5 to the 4th latch board from left. I reheated the +5V bus to that board, but the bad latching and dim display remained unchanged.
Gingerly putting a meter probe on the Vcc pin (pin 11, at the very bottom of the board – thanks, Murphy), I found there was no solid +5 there. We discussed the unpleasant but doable prospect of cutting all the bus lines and pulling the board out to resolder that pin. But Eric said boldly “I can fix that!”. After maybe 4 unsuccessful attempts at resoldering the pin, he resorted to soldering a new wire to the pin and running it to the +5 bus. It worked!
How he managed to solder a wire on the pin when he couldn’t solder it to the pad it was sitting on escapes me, but he did it. While not elegant, his new brown wire is in keeping with the current ugly wiring style of the display, and it accomplished the task without 
having to pull the board – so it’s a win. Thanks, Eric!
There’s still some funny artifact after each scroll (see clip at right), but that’s almost certainly just a coding error, not a hardware problem.
Good Show!
Ya, the part where the display wraps around at the end of the buffer is difficult.