Vintage Synth Repair

Hello guys,

I have been offered a cs20m but the owner is not sure whether 
everything's fine with it. My question is; what are the most common 
problems with this model I should be aware of? What about the memory? 
If the patches are lost, does it mean that the battery has leaked and 
destroyed the circuits? Or maybe non-corrosive batteries were used in 
CS ?

cheers
aero