Vintage Synth Repair

>Alright. I finally found the time to take a closer look at this thing.
>Now what I have found out so far is that one of the solder spots for
>the battery seems to be corroded and that seems to be the only thing
>there is other than that the connectors of IC16 are more or less
>covered in greenish-gray stuff (oxidation?), so are some of the
>resistors and diodes on their ends. What does that mean? needs new parts?

You should probably replace any component with corroded leads- shouldn't be 
anything expensive anyway.  The real problem is corroded traces on the 
board- if they're black looking then they'll have to be rewired.