Peak's momentary switch consists of the following parts:
(1) Switch body with an external o-ring. The body is threaded either directly into the body of the light, or into an adapter, depending on the flashlight body.
(2) Button with an o-ring. This is inserted into the aft end of the switch body. The front end of the button has a female thread to accept the battery contact piston.
(3) Button return spring. This beefy spring is housed within the body. When manually compressed it allows completion of the electrical circuit. Spring tension at all other times prevents battery contact with the negative terminal.
(4) Piston. At its aft end is a male thread. The piston is inserted into the front end of the switch body, through the button return spring, and then screwed into the front end of the button. This locks these four components together. Pistons are made in different lengths depending on application. The front end of the piston is bored out (except in QTC units) to accept the next component.
(5) Piston spring. Tension from the spring itself keeps it inside the piston.
(6) Battery contact button. Inserted into the piston spring and also held in place by spring tension. When the operating button is depressed, the battery contact button moves forward to contact the negative terminal of the battery, and the small piston spring exerts enough pressure to maintain the closed circuit but not so much that there is any chance of damage to the battery.
It sounds like the piston here has simply become unscrewed. Should be an easy fix.
