The old switch was a joke, it didn't work properly. Small Bear to the rescue!

The old switch is shown above, if you push the pedal down nothing happens. Then you push harder, compressing the rubber feet top right. Now the switch clicks, turning the Wah effect on or off.

Note that only about 1mm of smooth pedal travel activates the switch. This is very important, as it is most unlike a normal stomp switch which travels about 15mm sharply. Since stomp switches usually break before make, you can often get a "No Sound" position at the 0.5mm point. This is a reason why expensive pedals often have SPDT switches, it avoids the switch pop at the input. The output cap is pulled down by the 100K pot and can't pop.

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I removed the old switch and drilled a bigger hole.

Push the Carling down until it clicks and mark the height on the screw threads for reference. Then add the nuts, test and adjust so that the switch activates when you push the pedal down hard.

Because the output has a 100k to ground, you don't need an anti-pop resistor on the output. You might want one on the input, one or two Meg from ground to the input jack side of the 0.01uF input cap.