Slotted optos are not controlled by the 7-opto board as opto pairs. The slotted optos are placed directly on the switch matrix.

Once you fix the +12VU issue that you appear to have, take the balls out of the game and post an image of the 8x8 matrix shown on the dot matrix display when in T.1 Switch Edges.

You still have two balls in the trough. Take them out. They only add a variable to the equation that's not necessary.

1. SW32 is "Upper Right Jet" and closed. This is a spoon switch. Check the switch leaves.
2. SW81 is "Bookcase Open" and SW82 is "Bookcase Closed". One of these should closed but neither of them are. The interrupter cannot be interrupting both slotted optos at the same time. There is something wrong here.
3. SW84 is "Thing Down Opto" and SW85 is "Thing Up Opto". Same deal here as with the bookcase slotted optos. The interrupter cannot be interrupting both slotted optos at the same time.

The switch matrix only has (Darlington) drive transistors in the ULN2803A.

Here are some tests that you can do to help differentiate possible causes and locations.

1. Short (jump) J206-9 with any/all pins on J208 on the CPU board and see if the switches register.
2. In T.1 press SW86 "Grave 'A'" and see if it registers.
3. In T.1 press SW87 "Thing Eject Hole" and see if it registers.

• If the "jump" test on the CPU board passes there the problem is in the connector or the playfield wiring. If it fails you will need to repair this problem yourself or send the board out for repair.
• If SW86 and SW87 register then check the bookcase slotted opto board and the thing slotted opto board wiring. Check for the presence of power (+12VU) at the GRY-YEL wire and continuity with the switch matrix harness wires.
• If SW86 and SW87 do not register check the switch matrix harness wires looking for a break.

If you are unsure post images of the switch wiring and the slotted opto boards.

Those two switches are also in column 8. Your report indicates that all the switches in column 8 are out (2x bookcase, 2x thing, A and eject, 2x unused). This points to a more central reason rather than a peripheral reason. To differentiate the board versus the wiring you need to do the "jump" test. Once you have the results from that you will know where to look.

If you don't do this test, you could be looking in the playfield wiring for a problem that does not exist (because the problem is on the CPU board).

If the problem ends up being isolated to the CPU board AND you installed a brand new ULN2803A, it could be that the initial event that caused damage to the old ULN2803A caused further damage upstream to the 74LS374.

These are reasons why you need to do the investigation rather than shotgun (not saying that you are doing this but I have seen many examples of people who use the shotgun method on this forum).