Discussion about the Korg PolySix synthesizer

I bought Korg polysix and want to replace ic31 chip and battery but i have inspecting KLM 367a board and find bad things
Do i need to replace VR1 to VR 7? (under the board they are looking bad)
IC24 and IC 26 (HD14011BP) corrosion on the one of each legs,do i need to replace them or just re-solder?
And GR is bad how i can see. (Q1 GR � K30A GR11) (under the board they are looking bad)
Just want to know what i should replace and where i can find to buy all this stuff if i need?
Maybe i can test all of them with multimeter?
Here is a pics of board

http://groups.yahoo.com/group/PolySix/photos/album/1588581670/pic/list