Maglite end cap problem

[Dchall8]

At first I thought this was a battery problem. I have done many CR123 conversions on a Mag 2C, but this one didn't work. The light only illuminates when the flashlight end cap is almost completely unscrewed. I checked it with 2C batteries and it works exactly the same (or doesn't work exactly the same).

What can I do to fix it?

 

[Dchall8]

I diagnosed this with help from the Maglite website. There seems to be a defect in the tailcap or the body. The cap does not screw on far enough for the bare rim of the body to contact the bare aluminum on the tailcap. When I unscrew it just enough to slip a paper clip between the two contacts, it lights.

The reason it lights when mostly unscrewed is the anodizing is worn off on the threads at the end of the tailcap and the end of the body.

 

[LuxLuthor]

You might try taking off the tailcap O-ring, and tightening the cap down to see if you can force the threads to clear out a possible bad defect. If you do it by hand, I doubt you would damage the other threads, since so many of them will be engaged at the tightened position.

If that won't work, you could make a circle out of wire and make it tight enough so it stays between the tailcap O-ring and that outer contact edge...sort of a "poor man's conductive ring."

 

[yellow]

possibly You can find a copper or brass O ring and put it over the end cap treads?
or
measure the treads on cap and body, maybe the cap is just too long - then shorten it by hand.