My ~2 year old TL-3 also just started having intermittant failures. This light has seen very, very limited duty and was only on its second set of batteries. No rough usage at all. I put in a set of new batteries and noticed no light. Tried the old batteries, that I knew still had some juice, and still no light. Checked bulb and it was fine.
Finally, I found that by slapping it around some, the light would come on. That solves the problem for a while. Eventually, the light will stop working. Each time, if I slap it around, bang it on my leg, it will start working again. Something is loose, but I'm not an electronics guy, so I don't even know where to look to fix it.
Does your light recover at all?