Touching the contacts manually by hand may not be the best way to test it as it's probably more complex than just contacting the contacts individually. The contacts will be trying to calculate the velocity/speed from your 'press' between each of the two feet. I guess make sure you use an 'init' patch where velocity doesn't modulate anything, and I think for the key press to work you'd need both feet to cover all four of the PCB contacts, not just two of them, and to contact them in the correct order, and time/speed. I'm just guessing this, though.
PS> actually it would be easier to try taking off a rubber strip from one of your other octaves temporarily, fully install it into the 'faulty' PCB octave section and see if the key still doesn't work. This would ascertain whether it's the electronics/PCB or the rubber strip.
Other than that, you think it was directly caused by a coke/coffee spill? Coke/coffee have sugars and acid in them which can be pretty bad for PCBs.
Unless others chip in, I'm unsure what to advise further other than possibly contacting http://synthesizerservice.de
for advice, who are Access' service guys, although they are based in Germany.
BTW, pretty sure those 'small guys' look like diodes of some sort, rather than resistors. You'd need to take a close look at them to see what type/variant they are. Sadly I'm no diode expert, unfort'.