It's quite easy, actually.
From
Imägo Metrics:
Steps for adjusting the Click On/Off Switch.
* Remove the entire tail-cap from the body of the light by unscrewing it till it separates from the battery compartment.
*With the tail-cap firmly held in one hand, use the thumb of your free hand (no finger-nails!) to very firmly push the black rubber button in (it will click) until the entire switch mechanism feels like it's moving through the opposite side of the tail cap. This may require very firm pressure!
*Once the mechanism is completely out, remove the large conical-shaped coiled spring from it's 'seat', and set it aside.
*The rubber switch cap easily comes off to reveal the white plastic switch mechanism itself.
* Looking downwards at the button, turn the surrounding- white plastic crown anti-clockwise a few degrees (+ or - 20º ) inside its surrounding metal collar- to affect a noticeable degree of 'lightening' of the click switch tension.
*Conversely, turning the crown clockwise in the metal ring results in a 'hardening' of the switch tension.
Re-assemble the switch by replacing the rubber switch cap and re-inserting the switch mechanism- with a firm but careful push of a strategically positioned thumb or finger.
Once it's properly re-seated, replace the spring (wide end down) and make sure to properly seat it into it's dedicated inset cavity . This is important! If this step is too tricky, then back out the process and properly seat the spring before the switch is re-inserted into the tail cap.
Finally, re-screw the entire tail cap, and enjoy the adjusted click-switch. One or more re-adjustments may be required to fine-tune the switch button's travel/tension.
