Got this light about a month ago. Noticed quite soon that it sometimes changed the mode without me clicking the tail cap. It didn’t occur so often but it has gotten a lot worse over time. Seems like rapid movement and thuds trigger the next mode, not optimal when the thought use is on my bike 
Can I do something about this?
Hi,
Maybe the battery is losing contact, i.e., loose? A loose battery might look like the button being clicked off/on when the light is moved.
If so, try wrapping the battery to make it tighter in the tube and/or add a magnet to the end of the battery if it’s just not quite long enough?
Also, check the springs (both tailcap and the front, if there is one) to see if they’ve been bent/compressed?
Jim
Hi, thanks for responding!
I am using Sanyo 18650s’ that are sitting quite firmly inside, I tried wrapping them with some tape but it only got a tiny bit better. I checked the springs too and I can’t hear or feel the battery moving inside the tube.
I sent an email to Kaidomain anyways
Thanks again!
Try tightening the retaining ring in the tail too. It could be the switch is a little loose. I wouldn’t put a magnet in a battery tube.
+1
Tried adjusting the switch but it only got worse - now it’s so sensitive it’s useless with that switch, and I can’t get it back to the “half-okay” way it was first. Borrowed the switch from my amazingly great GTL C8 and it works better, but not perfect. Still sensitive to shocks.
Kaidomain will send me a new switch. Will post back when I get it.
Mode changes are caused by momentary interruptions of current. Something, somewhere in your light is making intermittent contact.
that kd xml2 looks very bright. hopefully theyre not all defective, i was thinking of buying a few.
UPDATE:
Got a new switch for my KD C8 - made no difference.
Only way of getting it to run somewhat as it should is to unscrew the tailcap halfway. It’s like this tailcap is to tight, I have tightened the switch as tight and far as i can in the tailcap but it’s still to tight.
Works decently with the deeper tail from my crappy GTL C8.
Try tightening the retaining ring. Maybe something is shorting out, or maybe the pill is loose in the host... Could be a few different things, but if it's not in the tail, it's got to be something in the pill
That sounds like the effect I get sometimes when the head spring is too long and the tailspring compresses so much that it flicks out sideways and then makes intermittent contact. I’d try pushing the spring right down to compress it, that’s normally worked for me.
I had the same problöem with my UF2100. Tried everything, magnets, tightening everything up etc. In the end, I noticed on of the bent metal part from the swith broke and lost contact. Thus, slight movement caused the light to flicker or change modes. I put a small solder spot to it and it works now.