
You might want to call or email the manufacturer. If they can't recommend anything, here's what I would do:
Pull the knobs off and open it up. Since the pots are on top, there could be beer residue inside of them. Use an electronic contact cleaner to flush out the pots. It's possible that the foot switches also have residue in them. I'm not sure if they can be flushed out. If they don't work, you might have to replace them.
If the circuit boards have beer residue on them, you could clean them with rubbing alcohol (isopropyl) and then let the alcohol dry. The old chemistry rule is "like dissolves like". Since beer is a mixture of various substances dissolved in water and ethyl alcohol, the isopropyl alcohol should dissolve these substances and flush them off. Gently use a clean toothbrush along with the alcohol if necessary. The isopropyl alcohol will evaporate without leaving any residue. 70% should work fine, but 91% would be better. Don't use that green alcohol or the dollar store 50% variety. Cheers!
