I removed the board and cleaned it. There was a little tiny bit of corrosion in the area of the Rude Solo Light, which I did my best to clean off with alcohol and cotton swabs. Someone must have spilled something - but not much - it was very localized. Anyway, I cleaned it all up, reseated the connectors, and put it back together. Problem not solved, but at least I know. The board works fine, except you can't set unity level. I guess I will just use the -20 and the clipping lights on each channel as a rough indicator. Oh well, the board does 99% of what I need it for, it came with a sweet road case, and I traded it for gear I hadn't used in more than 10 years. I guess you can't win them all. Thanks for the help and advice.