eMate 300 hardware questions

Apologies if this is too new to be officially on-topic, but as a slightly newer expression of Newton hardware, I hope an eMate question won't be completely inappropriate... I have these two eMates here... I got them at 'parts' prices because they were listed 'as-is' with "ribbon cable problems"... both fire up, show stuff on the screen, and neither one seems to have a working digitizer ("tablet"). One also has some dropped pixel rows on the left half of the screen - looks like a bad driver or bad line on the video RAM, but there's enough of the screen legible to see what's going on... I have taken the one with the video voids apart completely, and an trying to figure out where the problem might lie. After completely removing the video ribbon cable, I tried a white eraser on the contacts (vinyl, not abrasive like a pink pearl), and hooked up the display to the screen with the boards on the table... no change in behavior. The keyboard and CPU seem to work fine, and I'm getting reasonable behavior at an OS level, but no apparent perception of the stylus on the screen. So... are there any Newt experts that might be able to shed any light? I've been grubbing up FAQs left and right, but they don't go to this level of detail... at best, I have the Apple eMate service manual which _does_ describe in sufficient detail how to dismantle the beast, but it only references a PCMCIA card with pre-loaded diagnostics on it, nothing embedded in the ROM. :-( There don't appear to be any crimps or tears in the ribbon. I can't easily inspect the connectors on the motherboard or display, but there are no obvious external mechanical problems (i.e., the latches all seem to be good, no tool marks, etc.) Thanks for any pointers -ethan