My Infinity died...and raised

Last night my Infinity flashed once when I switched on, and died...I checked the battery and was full, them I cleaned the threads in the head and inside the body with a gun-patch and a brush.
A lot of black stuff was left in the patch, same stuff that I have wipped off from mini-maglites and others before, but that never stopped a light from working before!!
After reassembly it worked o.k. again.
So the black stuff prevented ground??
/ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif
Juan C.

Possibly. I've heard the black gunk is aluminium oxide and as I recall, it's not conductive (unlike aluminium itself). Surefire told me to clean the contacts at least every six months and I believe that applies to other lights too. Mag says "keep all bright surfaces bright" too.

That black stuff is a mixture of aluminum oxide and the lubricant used on the threads; and is not electrically conductive.
Best guess here is that the stuff acted like an insulater and interrupted the ground return path.