I can't track down an issue with one whole column of controlled lights.

Lamp Column 2 which controls four magnasave lights, 2 drain shields and Shoot Again. These lights flash on and off properly in the diagnostic lamp test. During play, they are stuck on or go on and off without regard for the rules. For example, shoot again stays on almost all the time. Its almost like they are on when they should be off, but it's not exactly that because sometimes the drain shield lights work according to the rules.

So far I have replaced:
Various drive transistors to get them all to light up on test individually.
IC 13 controlling columns 1 through 4 - no change.
IC 10 - the lamp driver PIA - no change in behavior.
all headers and connector pins redone.
Mosfets and zero ohm resistors mod done.
40 pin connector and header pins replaced.

What's next to diagnose or try? the only other thing I can think of is some kind of short on the wire to the PF for that column. I need to get a logic probe too. really appreciate any help. Thanks.

I found a ground touching between column 1 and column 2 - cleared that and things are better but not perfect. I'll go through tomorrow and check all the diodes and I may need to redo some of the board stuff if that ground caused previously replaced scr's to go bad again.