I have a Doctor Who pinball that I purchased in pretty rough condition about 10 years ago. As an amatuer, I was able to replace enough boards and fix it up enough to get it playing pretty well. A few of the optos didn't register, but it was very playable. Over the last 6 months, it started making beeps like the coin door switches were firing during the game. Wiggling a few wires around seemed to get it to stop. About a week ago it started making the noises again, then the playfield started raising/lowering to random positions, lots of errors were showing up on diagnostics. The volume suddenly went to maximum and i would not turn down using the volume control. I noticed a little corrosion below the battery bank, and thought maybe that had caused it. I ordered a rottendog MPU replacement board, but it didn't fix any of the problems and now the game just lights up, make a small amount of playfield movement then freezes. No DMD activity.......so, I'm interested in just starting at the beginning and trying to work my way through the machine slowly and check it part by part in a methodical manner. Any advice on resources would be greatly appreciated.