vfaq.com has a section on the leaking capacitors. There are three 'caps' on the ecu that go bad over time and you can order them from digikey.com (I believe that is the right name for the website).

Take the ECU out and take it to an electronics repair shop and have the guy solder the new caps on and clean the board.

All of this is contingent on the fact that it is in fact the caps that are leaking. Take the ECU out, open the cover and see if anything is oozing, or, if it smells like fish, you know it's leaky caps.