What vehicle is this and what tower does it have?
Regarding the plastic switch for the defender style vehicles:
If the switch gets screwed in too far, it can gall the plastic and prevent the center button from coming out rendering the switch inoperative.
Also a lot of the threads in the plastic switches are of poor quality.
I always chase the threads with a dye before installing.
The length of threads you screw in is how the switch is adjusted and there should be a nut to lock the switch in place.
It's plastic, so take care not to over tighten.