Fixed problem with flickering ultrafire cree light
I bought this cheap $20 80 lumen light from Dealexreme. The problem is it often flickers and changes modes. I think I fixed the problem by adjusting how the LED part is screwed into the head. If I unscrew it, it comes closer into contact with the batteries. The problem seems that it self-loosens as it vibrates. So I may apply some loctite to it to keep it in place.
placing a small piece of aluminum foil in the tailcap area between the spring an bottom of the battery also helps with changing modes..