Overtightened UF 501b

I had a a pair of Sanyo 18650 unprotected batteries without a button. They would work in most of my lights, but were too short for the UF 501b. I put a magnet on the base of the battery to lengthen it. Unfortunately the magnet was too thick, and I must have overtightened the tail cap. Now the light will not work with anything. I am not sure if it ruined the tail cap or the lamp.
Any idea as to what I might be able to do to make the light work? I am not very concerned, but do wonder.

Most likely you crushed the driver in the pill, or the switch. Maybe both.

quick way to see if it’s the switch or not is remove it and short the bottom of the battery against the housing using some wire or a paper clip etc, if the driver is ok it will turn on

Thanks for the help.
I shorted it and the it turned on. So the driver is OK, but is there a cheap tail cap to replace this one?


just remove the switch and see what damage you did to it as chances are it’s a quick fix with a soldering iron. Just use a screw driver or other implement in one of the 2 holes you see on the ring inside the tail to unscrew that to get the switch out.

Thanks, furythings. I unscrewed the switch, but did not see anything that was loose and needed soldering. I put it back together and it worked fine. I guess something got mis-aligned when I put too much force on it. I was ready to toss it, but you saved it for me.
Many thanks,