Dead pixels or...?

Yes, that looks like a ribbon-zebra-LCD contact problem. Carefully dismantling the assembly, cleaning the LCD and ribbon contacts and then getting it back together is risky, but then it isn't working now, so not that much to lose.

Jon

Thanks for the reply. The original LCD was very old, and it literally crumbled in my hands as I attempted to disassemble it from the board to clean the contacts.

Fortunately, I managed to find a lot of 3 unlit LCD displays on eBay that look like drop in replacements for the original - they use the same SMT OEM Hitachi display controller in a similar package, and even the PCB layout is very similar. The date code on the original board looks like 1986, these are from the early 1990s.

$3 plus shipping for the lot. Seems like a much easier solution...:)