While troubleshooting a no voice issue (music plays fine) on Earthshaker, I decided to start with the basics and check the diagnostics LEDs. The diagnostics LED 2 constantly blinks very quickly while the game is powered on (+5v and Blanking are constantly illuminated). At first I thought I was missing a blink pattern/number of blinks, but as long as the game is powered on, it constantly blinks; before/during/after a game. The game plays fine and does not report any other issues on the apha-numeric display during normal power cycle.
If I press the CPU diagnostic switch (switch 2) on the CPU board, it get a 'MEMPROT FAILURE' message briefly, but that is all. I replaced the batteries and don't see any evidence of battery damage. I also have the coin door closed during the test.
So, I can't find any other posts reporting this issue (if there is one, please let me know), so I thought I'd ask the community for advice on where to start. I am admittedly a newbie when it comes to solid state trouble shooting, so if you think a repair professional is recommended, let me know otherwise I'm up for troubleshooting/learning.