Gotta love this forum. Tried the battery from my EDC Ti, worked on low sometimes. Put a very thin small washer in the bottom of the tube, works perfect. No need to send it back to the orient. Thanks Gordo.
Crap. I completely forgot. I switched from using a small washer to using a tiny piece of folded tinfoil in the bottom of the tube. It has some give and take and works better.
If you have a washer or foil in the bottom of the tube, and tighten the head way too tight on High mode, you may have inadvertantly decreased the travel distance of the tab, and the light has very little spacing from Low to High mode.
To increase the spacing between Low and High mode, pull the tab out (on the head) just a tiny little bit until the spacing works for you. If the spacing has become too big, meaning it takes too much turning to go from Low to High mode, you can gently push the tab in a bit, at the edge of the tab.
Obviously, pushing and pulling the tab out too many times will weaken the tab joint to the point it will no longer hold enough spacing between Low and High mode.