Discussion about the Korg PolySix synthesizer

hi guys, hi again.
a have a story and a few questions.

a good year ago i bought a battery-leaked polysix and went through 2
synth repair services, just to end up fixing it myself. nobody could
fix it, after a month of being repaired troubles were still there. so
i opened it up, made the battery mod, located the few bad traces,
replaced 2 ICs and rewired the traces. and wow, it worked. it all
woked except for arpeggiator LED. it was always on. and a few bank and
patch LEDs were acting a bit funny too, but nothing serious.

yesterday i found out the subosc switch doesn't work. i knew soon
after "repairing" the synth that the battery corrosion will continue
to eat up traces, i should have removed all the damaged ones. so i
opened up the beast, print out all the schematics i have and got to
work.

after inspecting the schematics (and with the knowledge i acquired
since the last time) i found out that the arpeggio switch isn't even
connected to the programmer board (367).

so... the questions:

1. are *all* the electrolites worth replacing?
2. how on earth do you unsolder the main cpu socket (40pin i think)
without destroying all the vias? every IC i've unsoldered so far was a
tough job, unless i could clip the pins off.
3. how do i go about with my apeggiator problem? where should i look?
just replace everything in its LED's path?
4. what wire should i use for repairing the traces? i want it to be
really thin and isolated.
5. what do you recommend for cleaning the board? acetone? alcohol?

please guys, help me. i want to do this once and for all. it's my
favorite synth and i WILL make it work!

cheers,
jure