Quoted from pinlink:
Also on this, yes the CPU had some battery leakage and was effecting the game (ground shorts on multiple rows).
However, I have since replaced the CPU with a known working (and very clean) CPU. With this new CPU I had the game completely working other than the one opto sw75. Now here we are after I tried to fix the one bad opto. If only I had a time machine...
Corrosion on the female connectors? repin the connectors. Did this on mine, similar errors and I put in new MPU, had errors until I fixed connectors. Hope you can solve this problem.