New Stratum arrived not working right out of the box. Tried new batteries with no luck. Took tail cap off and pushed spring down/around and it worked when put back together, for a while. It then started to flicker when on and when I fooled with the tail cap again the spring came off completely. Light still does not work after reattaching the spring. How do you tell if it is a head or tail cap problem? Nice light while it worked. I know SF will make it right, but still kind of disappointed!