Thanx! I recall noticing this way back, but figured it was well known by everyone so I didn't bring it up... Plus being mentioned in the first posts... Now if we can get GearBest to update the product listing (BangGood has the same problem). It's an unusual limitation for a generally very good light, but I always dis-liked it was designed around a triple AA carrier, considering the standard amp limiting driver.
Thanks Djozz. I'll edit my post.
I should do my own homework. Have a good weekend Djozz. It can only get better, I hope.
Oh no, now I made a mess, I corrected my post above but you missed that: this light does indeed accept a 3xAAcarrier and thus the oshpark one you linked should work after all 
I think my tailcap switch is broken. Is that likely? If I make a connection manually, it lights, but I can’t get the tailcap to work…
Disassemble and reassemble tail cap.
If the light works without the tailcap, then the fault is in the tailcap. Could be poor connection in the threads, or the switch itself.
I did that and the plastic switch doesn’t seem to really be clicking. It’s just mushed down. I tried pulling it out, but I can’t get that switch to really click. Is it supposed to “click?”
Should click, the switch is probably bad.
What is the current (amp) rating of the switch? Is there a more robust one that will fit?
The stock switch's handle 5-6A easy, no prob. Sounds like a bad switch, assuming you are using the shorter unprotected cells.
It was working earlier, then I guess it broke. It was mushy from the start, but then it stopped working altogether. I’m just curious if I can replace it with a switch that will not break so easily…
Mine suddenly quit working too— just tonight … will troubleshoot tomorrow to see if tailcap switch issue … 
… sht …
Both of you using unprotected cells. Most protected cells are too long.
Yes, this happened when using unprotected 26650.
My switch quit last night as well. It was super sensitive before it quit also. Mine turned out to be the retaining ring being only held on by about a 1/2 thread. It was falling out. I tightened it up and it is perfect now.
By retaining ring, you mean the white plastic ring, right? Mine is tight.
Yes the white plastic ring. Mine was on the verge of falling out.
Mine was a broken solder joint… Repaired and golden now 
I got mine the other day and have been very pleased with it . I have 2 HD2010's and see this light as a nice comparable option .