Wow looks great, did you use the magic sponges for that ?
Tell you what.... my niece has a little girl of 1,5 years old. She was here yesterday while her mum and dad were working. I lost the little one out of sight for 15 seconds and she managed to find a pen and make a nice "drawing" on our coffee table !!!!! (Maybe I am also spoilt, my son never did these kind of things.....)
Since I was working on the Ms.Pac cab anyway, I had a magic eraser right at hand. I didn't doubt and went for it. The ink was gone very quickly !
I do have to put some new "white wash" on the table now but even so, I was very happy that the ink was gone like that !

OK, back on topic: I have always hated the fact that Atari's trackballs are mounted with those bolts. They always seem to get "in the way" when playing. Maybe it's just me. But I remember I had a friend weld some threaded rods on my Puckman CP to invisibly mount the joystick from the backside. This was because there were a lot of extra holes made which I closed with Bondo anyway. Since you will have to replace the CPO anyway, maybe you can find someone who can do this too.
Yes it's not original, but yes it looks better and especially plays a lot better.
If my Centipede didn't have a new CPO already installed I would ask my friend to do it on that one....it's just something that annoys me a lot during play....