I should have done this long ago, but for whatever reason, didn't. My problems with Centipede convinced me that I needed to take off the ICs and clean the contacts of Dig Dug as well. This cleaning was probably a good idea, considering that they were quite corroded. However, a few chips had corroded to the point where the pins were extremely brittle... and one snapped right off!
PCB cleanup (continued)
The new custom chips arrived and after installing them (and reseating the other chips), Dig Dug is alive and well.
Dig Dug is now finished! I might make a new back door one of these days, as the original door was tossed out in favor of a cheap piece of thin plywood. But, for now it's completely done.