A picky point, but concerning DanDude
Clean any acid-infected surface with isopropyl alcohol only!
It's _alkali_ not acid. NiCds leak alkali (still corrosive though) Redrumloa has ebay auctions where he sells NiMH batteries that are the same size and voltage and solder right in place of the old ones. Maybe you can do a deal directly with him for less? Tell him I sent you. (like that will help any :-) )
One other thing, a number of the A4000s were made with a 3.0 kickstart, you'll want to make sure that you get a 3.1 kickstart.