I am currently working on a Blackout (System 6) which is prone to lockups. So far I have basically gone "by the book" at marvin3m, and have rebuilt the voltage supplies, electrolytic caps, and moved the battery holder off the CPU board (no corrosion!). Next up will be replacing the 40-pin inter-board header/connecter pins, as I suspect this is my problem (also from marvin3m).
So far for me, it doesn't seem like any more or less work than games from other manufacturers of that era.