Since power is switched in the lamp matrix, won't he see 0 voltage if all the lamps are OFF? I'd think he'd only see voltage if there is a lamp ON in the same column as the one he's measuring at. ...unless you're looking for a locked-ON column. Then he'd need to measure at a bulb in *each* of the columns (or at all the pins on the column connector) because it could be any of the columns that's causing the problem.

I'm looking forward to resolution on this one.

Uh oh.

Solenoids enable when you go into diagnostic mode...

Man, I've been following this thread from the beginning, but now, if it were me, in my own beloved Sorcerer, I'd fix it like this...
http://www.pinballpcb.com/System9-11cMainBoard.html

And then I'd throw in some of this so everything "matches"...
http://www.pinballpcb.com/Sys7-11bPowerSupply.htm
http://www.pinballpcb.com/FlipperPowerSupply.html
http://www.pinballpcb.com/SpeechBoard.html

Their power supplies are sexy and I think they're the only folks who have made a System 9 board.