[BrianG]

There's not much current flowing through these switches - they are probably just grounding a pull-up resistor or something just to signify 0 or 1 to a logic input. However, if the circuit has a high input impedance (which this does), any resistance in the switch may not trip the circuit like it is supposed to. Corrosion, dust, etc all increase contact resistance, so instead of a solid 0 or 1, the circuit sees something in between.

If a switch is desired, go to RadioShack and get one of their closed frame toggle switches. I personally like the mini toggles rated for 5A. No, 5A is way overkill, but a higher current switch will have a much more solid "snap" actuation, which is helpful to prevent hard jolts from triggering it accidentally. Also, I cut down the toggle part a bit so there is less weight for inertia to act upon.