Every effect pedal tweaker know this kind of switch: the momentary SPST switch:
I myself often need these ones, so I often order some of these on eBay. And sometimes it happens that they are shipped badly configured. Let me explain: what you’re expecting that kind of switch is OFF-(ON): if you push it it closes the circuit; if you release it, the circuit opens. That’s why it’s called “momentary”. However, they’re sometimes shipped as ON-(OFF), just the opposite of what we want!
But it’s not a problem: most of the time they can be modified:
These ones have two screws, so let’s open them:
When the switch is pushed (black part), the part labeled as “A” swings to the left. And when parts A and B are fitted together, it causes the bottom of part B to slide to the right, far from metallic contacts. When the switch is released, the opposite happens.
To change the switch mode to OFF-(ON), you just need to modify the orientation of both parts:
There you go. Beware that both parts fit well and screw them back together. Your switch should click as it used to.