Light has 20 ~30 hrs. on it. Maybe. Always on L or M. It started flickering a few months ago. Then it became reluctant to power up at all unless tried multiple times. Now it's just dead. New cell does nothing. Removed lens & reflector, put pressure on emitter to make sure it wasn't loose. Never used anything in it except NiMH or alkies. Everything's clean. I can swap the head with another operational TK05 and the problem follows the head. No response from a PM to seller Thorfire weeks ago.
I like the light & would like to salvage it. Any aftermarket driver options?
You changed the head and it’s the same issue or are you swapping the bad head on a known good light? If the problem follows the head then it’s either a dead driver or led. I’m not familiar with that light but see if it has a retaining ring for the driver. If there is, loosen it a bit and tighten it down (not too tight), sometimes they can loosen from heat cycling and get a bad connection. Test the led with your multimeter diode check function to see if it lights up. Touch the + probe to the led+ and - probe to the led- and see if it lights up (unsolder the driver leads first). If it doesn’t light up (but your readout shows voltage) or it does light up, then chances are it’s the driver or a short somewhere.
Inoperative head on a different tube/tailcap is still dead. Good head on the tube the bad head came from works OK. Not much to go wrong on a tube & plain tailcap.
A pin on my favorite ring tool broke when attempting to unscrew the ring. That puppy is stuck tight! Until I can figure out how to unscrew the ring, I'm at a standstill.
Thank You caramba! That's helpful. I'll update when progress is made.