I just want to comment on this part right here.
I hope you're handy with a soldering iron(not joking in the least). If you're not, you soon will be.

I'm going to recommend(based on Ian's post) that you get an IC Extractor if you don't have one. You're going to need it.
Be VERY careful when plugging the boards into the harness. When I removed the filter board in mine, I wasn't as careful as I should have been when hooking the individual boards up.... and this happened to the AR-II board:
If that happens, don't panic. Those parts are easy to come by, and take maybe 10 minutes to remove and replace.
If it hasn't been done already, do the "test point" mod, you'll save yourself a ton of headaches later on. It's also pretty easy to do.
Again, if it hasn't been done already: You can use one of several ways to fix the high score table. A 3-AA battery adapter, a 3.6v NiCad battery(for say, a cordless phone), or the chip replacement you can get from some places online. I found them difficult to locate, so I went with the NiCad.