You’re holding your tongue on the wrong side of your mouth while finagling the driver…. 
Haha that’s probably it, probably easier than Iam making it.
The L6, or at least mine, doesn’t have the excessively long leads like most manufacturer’s builds, so you need to de-solder the leads from the emitter mcpcb in order for the driver to be lifted. The switch wires should be long enough to do what you want without removing them.
I have Thermal Paste all over the leads from my swapping out the factory mcpcb with a larger MaxToch version.
How are you liking the U21?
Ahhh, think I toasted it - the driver. Somehow the main LED doesn't work anymore, but the dragon eye thingy mode works fine. This was an engineering proto unit anyways. Was gonna ask for a replacement driver, but really want to replace it with my own ATtiny 85 FET+1/Narsil, then use a de-domed XM-L2 U4 most likely. Better throw, less lumens. I really like the host, but I'll lose the USB charging, but can use at least one of the switch LED's for battery monitoring, LVP, and locator LED - all supported in Narsil, plus the smooth ramping for a thrower should be nice - see how it works out.
Just to mention that all the reviews of the Liitokala 26650 I have seen show at least 5,000mah capacity, my own review included.
Here is the link to the reviews of the cell on this site LiitoKala 26650-50A 5000mah 26650 - great first impressions
Some posters have found that they won”t work in series without a magnet or other spacer to make contact but some find they do.
I have 6 of the cells & mine make contact fine in series in both my S70 & Z1 with no spacer :+1:
Hey Tom, have you managed to get Narsil running in your L6 yet? I’d love to get Narsil running in my L6 and wondering about the best way to go about it.
Yes Narsil on a light like this sound so sweet
But of course there are challenges for hardware / software combo designed for 2,7-4,2V input Fet+1 to run on 5,7-8,4V input.
Thanks for the info. I see your testing in the Lii-500 show over 5000mAh.
The photos on Gearbest and ali express appear to be true flat tops (recessed) that wouldn’t make contact. But the cells you received actually have a raised (protruding) + end? Did you get your LK26650 cells here?: Snow White’s store Electronics
…………………
…………………
These are looking good for the money, but with the inconsistencies you mentioned about the flat tops and the reports of lower capacity, I’m concerned there may be some fake/re-wrapped cells out there. I’ll give them a shot, just have to decide where to buy them to hopefully get good ones.
No inconsistencies reported.
They are all flat tops.
All tests by many different members using different analysers have shown over 5,000mah.
The working/not working in series is more down to differences in the lights I think rather than differences in the cells.
In some lights they work in series without spacers in some they don”t.
That could just be down to the lights themselves, maybe having softer springs.
I bought my cells from Aliexpress & Gearbest, I can”t remember the actual stores I am sorry.
I also have Keeppower 5200mah, Basen 4,500mah & Thorfire 5000mah 26650”s & find these Liitokala”s the best performing cell & only about $5 a cell :+1:
Just checked Aliexpress purchase was from Snow White.
Gearbest purchase was here http://www.gearbest.com/batteries/pp_360842.html
I must admit that with the cells being true flat tops I was surprised that they worked for me in series without a spacer, but adding a spacer such as a small magnet or a proper spring spacer that are widely available for peanuts would be no big deal.
Also with the L6 having LVP them being non protected is not an issue & TBH I rarely use protected cells in any of my lights nowadays.
Gearbest seems lowest price at ~$12,50 for 2 liitokala 26650 cells
Think I will order a pair for the L6 if they don’t carry the heters
Edit: Nvm heters are back and I like the S70 and L6 to use the same cells.
Sorry, haven't looked at it yet. Main issue is needing an LDO, and adding support of just a FET (no 7135), then the battery level update. I know I got LDO parts, know I got blank drivers w/LDO support, just no chance to check it all out.
4 hours sleep last night doesn't help (latest Narsil release), plus the work/make money thing... 
I got 4 of those Liitokala 26650's from GB on order now, along with 4 VTC5's and 2 GA cells ($47 order in total, every top notch cell for under $5) - deals too good to not take advantage of. If the Liitokala's actually perform better then the best EFEST 4200's, it makes it the best 26650 cell, given the capacity at a true 5000.
I will be using Shockli 26650 IMR 4200mAh purchased from Mountain Electronics. These batteries have good results from being tested at: Battery test-review 26650 comparator.
For the Shockli, I would not call a 0.6 calculated ohm internal resistance a top performer though. It's probably less high performing than a EFEST 4200. The VapPower 4200 tested better at 0.5 ohms, and higher voltage through-out the discharge curves.
Unfortunately HKJ is not testing the best available cells out there, for whatever reason, so we can't compare the best against the best. He's got a queue of provided cells, and the best ones aren't getting in to that queue.
The better BASEN's are a better deal, though sourcing good ones has been problematic. But of the Liitokala have true 0.4 or 0.5 ohm performance at 5000 mAh, it then would be the best cell I would think. Again, we may never see them tested by HKJ though, just like the EFEST IMR 4200's.
Thank you for the updated information!
I should clarify though - think he's tested more cells than he lists, because of the pair, if the differences between the 2 cells are significant enough, he doesn't post the results, deemed unreliable. I vaguely think this happened with the BASEN's, maybe? Or was that mooch? When he's asked for suggestions, I begged him to test the popular cells we use for high performance, but it didn't happen totally, though did partially - but 26650's didn't seem to be a priority.
Thank you again for this information to be added to what needs to be a bigger data pool for a general public.
I have tried to navigate 26650 batteries and flashlights, but given the inadequate available information it is all to easy to take a misguided turn.
I find it interesting that among 18650 cells there are a few top brand name players that rule the roost. But when it comes to 26650’s there are quite a few reportedly good cells of much lesser known name branding. That does indeed make it more difficult to weed out the good ones and the best deals.
I bought 4 of the Basens when they were all the rage, I use some King Kong cells as well as some older LiNiMnCo cells from Powerizer (think I’m remembering that correctly) and like so many others, I have some EVVA’s as well. But my primary go-to 26650’s are once again Efests. I have far more Efest cells than any other brand, in every size.