Same cable works with the passive greyscale and it works fine. I think it's either the controller on the screen, or possibly a trace/line to the LCD grid has been damaged/broken. But not really sure..

Since the PowerBook hosts this website, I am not incredibly worried as it sits with the screen off. It's been designated pretty much as an old webserver. Seems to run well, even with the DDoS I had several weeks ago. That was fun, but the PowerBook, once I got her back online did well (she crashed within the first few minutes of the attack) and has been having excellent record of run time (as much as close to 142 days non-stop)