MicroKorg - nasty liquid damage - program numbers don't work

[spunko]

The microkorg was fine until the cat used it as a urinal, and I didn't notice for several days.
When I used it, everthing worked except the program numbers, and then I realized the nasty true.
I cleaned it meticulously, using thiner, alcohol and contact cleaner depending on the part I was washing.
I didn't notice any rust or corrosion. There was only one leaky capacitor near the 9v power jack so I changed it, but I think it was already leaky before the piss disaster because my microkorg is really old.
When tested after the cleaning and cap replacement it was the same, everything works except the program numbers.
Number 1 stays on forever and I can't change it, but with midi everthing works even the numbers.

Does anyone have any idea of how to adress this?