Brian:

Read your post on CPF and need more info as I know nothing about Arc lights in particular but have dealt with mechanical things of all types most of my life.

I have a Maglight Solitare on my keychain with a twist CCW to turn on and tighten CW to turn off the light. The switch is a pressure sensitive membrane surrounding the perimeter of the bulb and its mounting holes.

If the Arc works in a similar fashion, I would look at the possibility of dirt not allowing the membrane switch to close, or bad engineering on the cap that does not have a deep enough flange in the caps interior to push on the membrane switch. The worst case scenerio would be a cheap contact material used in the membrane switch which is oxidizing.

If you get an answer that works, let me know how close I was to being correct.

Good luck!

Bountyhunter

Thanks for the info. That makes sense too. I need to take a closer look at it. If I figure it out I will let you know how. If I can't then I'll break it down and post some high res pics so you can see what makes it tick.

The Arc AAA doesn't have a switch in the typical sense. When the head is turned it screws further into the barrel and makes contact with the battery. As long as you have cleaned the contacts in the bottom of the tube, the head, and the threads odds are that the electronics are the culprit. Good luck with repairing your Arc, and yes it is one of the best lights i have used too.

What makes the connection between the top and bottom contacts? The tube itself?

That's how it works with all metal-bodied flashlights I've ever seen. Maglight included.