Just a little update, got myself bunch of these, using black one at the moment, rather bright for the size and 3lm version is really useful, Im glad I got this quality light ;)!
Out of 5 lights one was DOA, one started to work on low only and the third one is also having problems with high mode.
Now looking towards getting other quality AA/AAA lights with good low and runtimes :D!
https://budgetlightforum.com/t/-/12765
There is a fix for one of your problems in the above link veer.
Nope, sorry, it works only when light is stuck on high, doesnt work on low and despite that I even tried it but its useless 
Little update - left that light unused for one day and it started to work again, thats weird.
Either way, Ti sent me replacement and I received it today, emitter not as nicely centered as on first black one, but on light this size and output it doesnt show up in real life usage :)!
Can i use a 10440 with this flashlight?
I don't think so, I've been doing it for the past month though.
see bottom of OP: https://budgetlightforum.com/t/-/8156
Thanks kreisler!