OK, thanks guys. This one does basically doesn't work - you can barely see the display at night with the backlighting on, and not really much at all in daylight. It's basically useless, and I was just going to remove it. There are 3 others that work better, all in a line. This one has suffered from moisture intrusion more than the other 3.
I can replace pretty much my whole system for the price
of a single
20/20 display. This technology is at least 20 years old and this particular unit IS 20 years old...