Well that was fast and easy. Thank goodness.
It turns out the culprit was the Astec power supply. It had a dry
solder joint on the "DC OK" line. A few drops of fresh solder later
and the terminal is good as new (well, as good as any 35-year-old
terminal can be, anyway)
While I was inside, I removed a very old but thankfully non-leaky
battery. Need to figure out a new battery if I want to preserve
settings.
If anyone is interested, I did dump the terminal's ROMs while I had it
open. They're here:
http://www.loomcom.com/3b2/att_4425_rom
-Seth
--
Seth Morabito
seth at
loomcom.com