LGCubana said:
There maybe an easy fix. Try cleaning the positive contact point on the rear of the light's head with a pencil eraser.
Worked for me on an Ultrafire CR2 model.
Yeah, that's a good point.
Also, it's pretty easy to isolate the problem as being the switch or not:
1) tighten the head down to make sure it's making good contact. This isn't as critical with the L1DCE since contact also goes through the threads, but it's a good idea.
2) remove the tailcap.
3) insert battery (or use battery already inserted) making sure the + side is toward the head and the - side is exposed.
4) use a paperclip or other piece of conductive material (metal, wire, etc.) and touch one end to the battery - and the other end to the bare aluminum end of the body.
This method makes contact from the battery - to the light's - (which is the body itself). If it lights up, the problem is in the switch. If it does not light up and you are sure you are making contact between the good battery and the bare aluminum of the body, the problem is in the head of the light.