First off, I'd recommend asking about repair details from several techs. Things like voltage caps are standard pieces that can still be located. Likewise with key contacts, etc. If the main CPU goes, you're simply screwed and far from home, as companies can only keep those molds for so long before they move on to the next model, leaving you with no options. That's one of the more annoying aspects of the electronics biz, but a reality all the same.
Second, when/if you get them back in usable shape, leave them at home, period. Instruments of that age don't do "road" well
and will behave better if left in one place. Sampling them is highly recommended.
I'd suggest these possible repair sources:
*e-mail Analogics at flattop@suite224.net
*www.analogsynths.com
*Caruso music at caruso.net
*roguemusic.com
*Used Gear By Mail at ugbm.com
One or more of these outlets is almost certain to help you get a handle on resucitating your Korgs. Hope that helps.