You can test those switches with a DMM. Clip the leads to the terminals, set DMM to continuity and press the button. If you get a tone the switch if fine. If you don't get a tone switch side on the switch (dual pole) and try again as they have 2 switches internally. You may find that despite the liquid they still work.
I have found in machines with this sort of damage the interconnect for the coin door always is affected too. You can test the crimps through the interconnect by putting your DMM leads in each side. I just fixed a Taxi that was having this same problem.

Siegecraft makes a cheap little board that plugs into the mpu that gives you alternate diagnostic buttons. It is very handy to have one of these on hand.