Discussion about the Korg PolySix synthesizer

had my polysix sitting idle for about 5 years now, had given up on it 
because of the keyboard problems but got it out for my kids to play 
with recently.  then I found out about the battery problem when I  
went looking for instructions on how to use it.

well, the battery is out now, no real damage visible, but a bit of 
green around the leads on the IC.  

Question, if I dont clean it will it continue to corrode and get 
worse?  or is it mostly ok to just leave it now that the battery is 
out.

Got all the keys working perfectly thanks to the keyboard cleaning 
links.  well, all except for 2.   then suddenly one of them just came 
back on its own.  then the other started ( except it only plays when 
the key is on its way back up ! ! )

also, anyone have any suggestions on cheap midi upgrades? 
mosly I want to be able to send and receive keyboard info, not really 
concerned about patch info.

thanks

bill