This should help
how do you disassemble fenix tailcaps?
Different brand, same principle.
Norm
No Norm, wrong type of switch...
Yea, if you bother to register!
The problem isn't to disassemble, but to put together again.
This is how I managed to do it:
1/ Pull the spring
2/ Just remove the boot by pulling it out
3/ Push a screwdriver onto the center "button" from outside, and loosen the hex screw from inside
4/ Loosen/unscrew the outer plate with needle-nose pliers
5/ Replace the rubber booth, and secure the threaded plate (from step #4) with the little button-part - do this "upside down"
Now the tricky bit...
6/ Place the tailcap, rubber down, on a hard surface, and insert the metal disc with the hex screw
7/ Vigorously push the tailcap onto the surface, creating friction between the rubber and the little center push button, and secure the hex screw
8/ Refit the spring