I finished up Sharp Shooter II this afternoon and got some solid game playing time in!
First the display issues: With them all pulled out I tested the transistors on all 5 display boards and they all tested good. Moved on to the 74LS379's and compared some readings to the working Old Coney Island displays and they were different, so I gave it a shot and replaced the 74LS379 on one of them and everything was working perfect in game and test mode. I ended up replacing that same chip on all 5 displays (adding a socket obviously) to fix all 5 of the faulty displays. I've got no idea what happened to this thing before I had it that would have taken out that chip on all 5 displays, but its all good now!
Here is the break down on the display issues in case someone has something similar happening:
Player 1 display - all digits out and shows nothing, replaced 74LS379
Player 2 display - all digits out and caused mpu to not boot fully, replaced 74LS379
Player 3 display - only showed 1's on all digits all the time, replaced 74LS379
Player 4 display - only showed 4's on all digits all the time, replaced 74LS379
ball/credit display - only showed 0's on all digits all the time, replaced 74LS379
After installing a new ball, rubbers, lights, doing some switch cleaning and adjustments, and cleaning up the drop target bank so it resets properly, we are good to go!
Another project done..... on to the next.