I approached Surefire many months ago because my base switch on the E1E (now an E1L in fact since I converted to the LED head) ...... was intermittent ....... and they sent me a new switch. The replacement was in fact a click-on/click-off as against original which was the pressure button and twist on.

I began to realize of late that the newer switch seemed less than 100% and so inspected more closely. Turns out seemingly that the contact at base of LED head is some sorta solder type material - and I could see mine was darkened thru slight corrosion/oxidation.

I carefully polished it up with some 600 grit and that seems to have improved matters. I still think the pressure type switch was failing but - see now that this as I have described is also a potential problem. The contact between that LED head base protrusion and + of battery will of course be high resistance if corroded.

Worth noting for any folks out there who might experience anything similar - make sure that LED head contact 'button'' is clean.