This is a tech post for future problems you might have.

I took on a repair recently for a WMS Laser Cue where the owner used a MPU 327 to resolve multiple issues with the original boards. He swapped J2 and J6 (they are keyed alike) and his displays stopped working. In short - he fried IC6 (74HCT154) and it has to be replaced (you will have to add socket unless yours already has one). You can use the original 74HCT154 in the Rottendog board or a 74154 if you can find one. It is likely that a 74LS154 will also work. This fix was tested when the output of the '154 heads to a Pinscore board, but should also with the original WMS Display Driver board.

Here is my log of the problem for those that want to see - or could use an example of how to log your electronics troubleshooting:

SYMPTOM: Only one 7 segment display is working on 2 of the 5 displays. User has a Pinscore display replacement. Using the test button on the display yields 2 "8's" where the two 7 segs are working.
DIAGNOSTIC: Pinscore display history shows it is new. Passing this as problem. Inspection of connections to MPU 327 identify that owner swapped J2 with J6. Both are keyed alike. Owner doesn't have manual in game, IPDB doesn't have schematics. Based upon Jungle Lord Schematics, user sent 12V on Pin 9 of the J6 connector. These are coming from the 74HCT154 4 to 16 decoder. 12V was sent to an OUTPUT of the decoder, likely destroying most or all of the IC.
PROCEDURE 1: 74HCT154 is not socketed. Try swap of PIA feeding the decoder since it is socketed.
RESULT: No change - reverting.
PROCEDURE 2: Remove and replace 74HCT154. Add socket.
RESULT: Problem resolved.
NOTE: Consider using 74154 from NOS to see if TTL levels drive the display driver board correctly. They should be more powerful than the HCT.
UPDATE: 74154 also works correctly.

If you are new to electronics and want to learn more about components, schematics, and troubleshooting, plan to attend my 2 hour seminar at Pinball Expo 2018!
-Rob Craig