I'm currently bringing a pair of aero tables back to life.
You can see the condition I received them in and the start of work in this thread on Arcade Otaku. I'll post the rest of the process here.
Today I populated the beautiful control panel with LS40s and sanwa buttons and cleaned up the side art sections.
These side art bits have suffered a fair bit. The rubber is a little perished on one or two of them and the metal section in the middle is corroded. It looks exactly like acid corrosion you may have seen in something you left batteries in. It has the characteristic smell and the powdery residue.
The metal bits were covered in several clear plastic layers. The top layer peeled off easily in one piece (you can just see it being pulled back at the top of htis photo. The layers below were more firmly attached and only peel off in very small sections. I wanted to leave as much as possible as I think it may offer some protection from further damage. On the other hand I want it to look as nice as possible. It's a compromise but I've removed more layers in some parts than others. It looks good unless you study it very closely.
Post clean up they look like this. It's certainly a big improvement but they don't look new.
You can see in the above photo the example of a damaged section. I scraped away at the corroded patches with a blade. this was about as good as I could get them. The tarnished sections can't easily be totally removed, at least not without scratching the panels up pretty badly. Around it you can see where I've removed a section of one of the clear layers but left it where I can. It's not noticeable except in close ups like this.
They aren't perfect but I'm happy enough with them.