I changed o-ring to little thicker (about 19x2mm). 19mm o-ring needed some stretchning ’cause that heads diameter is 30mm (bigger diameter rings that I had was too thick). But it snaped nicely in its place.
Now that head is stiff. It won’t move by accident, I’m pretty sure about that. I “hammered” with flashlight few times hard and that head remained same place where I left it.
This is how it should have worked in first place. 
Ordered/shipped on 11/12, any day now hopefully. Was looking for a light to use a single 26650, and the flood on this one sounds nice. Looks like it need some TLC - when I get it, I'll be studying this thread carefully - thanks for all the info!!
I would be interested in upgrading to a KD V2 3.04A driver, maybe add 1-2 380's to it (3.4A-3.8A). It looks like an aluminum pill however - wonder if there's a brass ring to solder to. If it's solid aluminum, it's a pain but I'm experienced with the cheap stuff!
Just got this light, bad news with this light - no flat surface/heat sink for the LED star mount. LED is loose, floating, and hangs on the edges, same as a driver does on the opposite end of the pill. I've seen this before in a cheap zoomie. Does anyone have any ideas? I could use good thermal grease or thermal epoxy on the edges, or press fit something inside the pill, but to get it aligned perfectly to the back of the star may be a nightmare. There is plenty of depth in the pill to work with.
I ordered the Poppas S7, that's what the links for the 878 take you to now - looks like Manafont changed the model name listed but appears to be the identical light, accept maybe for the hole at the top of the pill 
...
Solved it - I got several brass pills from FancyFlashLights and sanded one down to build a press-fit insert, flush fit behind the star - worked well, also added copper/solder into it for additional heat sinking. I'll post pics. I'm using a 2nd brass pill to convert the 20mm driver mount to 17. This light has a big aluminum pill, massive now will the copper, solder, 2 brass pills, so I'm putting in a KD V2 running 3.8 amps (10*7135).
Update: I got it working at 3.4A, still will update it to 3.8A. At 3.4A, it's nice, real nice - my most powerful zoomie but all my other zoomies are cheap and small. With a 26650 and all the mass I added, it's heavy, feels solid. Really like the width of it in full flood (truly lights up a full room, more than a HD2010 or modded C8) and in throw, the square image is smaller than my other T6/U2 FTT's and it throws pretty well - not as much as a HD2010, Jacob, or maybe even my modded C8 at 3.8A/U3. It takes quite a while to get warm/hot which is what I expected with all thah mass - used Arctic Silver grease, not epoxy, on the star because the reflector screws down onto the star to keep it firmly in place.
More Updates (12/09/12 eve):
Got it working at 3.8A now - really like this light now! Using a King Kong, lot of mass, tailstands, just need to add a nice GITD lanyard and a holster.
Work Bench:
The hole under where the star was, and the sanded down pill to use as the star backing:
Close up of the sanded down pill:
Sanded down pill with the original pill, before sanding:
After mounted:
Showing the heat sink additions (cut copper wire, held together with solder), and the next pill sanded down for mounting the 20mm driver:
Up close view of sanded pill before press-fitting into place:
Final assembly (no pic) has the original pill with the star backing pill with heat sink filler, and the other brass pill for mounting the 17mm driver in. This thing is now heavy!
Thanks Tom for the photos! Never realized this one had a hollow pill. I've run mine on a King Kong unprotected at 4.0A+ for a few minutes at a time too!.
BTW - is that an older Kenwood receiver I spot down there under your workbench?
-Garry
Garry - could be the original 878 was ok, but the Poppas S7 replacement has it missing. If you go to the link for the 878, you get the S7 light with the earlier 878 reviews posted, including yours! Think they cheapened out in the redesign. Thought I saw a pic on BLF of the 878 pill showing it had the full backing for the star.
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Update: hhhmm, not a Kenwood, but kind of got stuck there - nowhere else to go with it for now.
Garry - did you verify you have the 878? Was wondering if the S7 model cheaped out. here's the 878 pill posted back in April and it definitely shows a solid backing behind the star, but no thermal grease: https://budgetlightforum.com/t/-/7687. You posted there as well.
Ok, I haven't opened mine up (nor do I remember investigating this), but I am pretty sure your hunch is correct that they cheapened things up and at least had the decency to change the model number while doing so. Mine is definitely the older 878 model. Could you (or have you already) post a review over at Manafont with your findings on the hollow pill?
So, if you don't mind me asking, what is it? (I'm just curious.)
-Garry
Really like this light now: U2, 3.8A KD V2 driver, and all that heat-sinking - takes a few mins at least before warming up. Yes - I should definitely post a review up there, maybe this eve, at work now.
Hhmmm, trying to recall about the receiver, forgot to check last night, it's a name brand - good for it's time. Ran out of space in the living room for it when upgraded to a big flat screen. @work now, will check tonight and let u know - it's bugging me now 
. Onkyo or Yamaha, thats' it! I'll check tonight.
I see now the older Kenwood's I was thinking of don't look like that at all on the rear. Looking again I'm thinking your receiver isn't as old I first thought. I've kind of had a thing for older receivers. I'm still using my 1990 Pioneer VSX-4400 bought when I was 14. (I have yet to upgrade to a modern home theater receiver.) I also have a big ol' tank Kenwood (not sure of the model number) which is all analog from the mid '70's that just looks cool with all it's knobs and dials.
-Garry
Finally posted the review on this new S7 - 2 stars, "Dont Buy" because of the top missing from the pill. Also mentioned earlier posted reviews were on a different model.
Looks like an Onkyo to me, late 90’s to early 2000’s maybe?
Let us know.
Thanks,
Keith (sold Hi-Fi for 15 years)
Oh - forgot to post this -> it's a Yamaha, model HTR-5560, 290 watts. Time frame is about right, not sure, couldn't find a date on it.
I have a Fasttech SKU, 1864903, 
which they call a TrustFire 878, though there is no brand or model information on the light. Since Fasttech tends to be reliable, I suppose it is really made by TrustFire but that TrustFire either had a fit of modesty or a broken engraving machine and left their name off. I intend to read this review and report any interesting differences. I found it going through Fasttech’s web site.
The first difference is that it comes with a 4xAAA carrier that also fits in other 26650 lights. So it would have good output as a gift to a non lightoholic. And mine did not come with a 18650 spacer.
It will be useful to me at least as a hanging lamp, because of the long run time and the better light distribution of a zoomy with a diffuser, compared to a reflector light with a diffuser.
2 The lens is captivated in the bezel ring by crimping, as it is usually done, not by glue, but that might be a mistake in the OP.
I measure 0.9A at 3.7 V and 1.1 A at 4.2 V. This appears that TrustFire has opted for more run time than Poppas (another poor brand name choice), but the slight dependance of current on voltage is unusual in this price range.
To hold the star in, there is a neat screw in aluminum plate, dark to reduce rings, and a clear insulating disc.
But the pill is hollow and there is no thermal compound between the pill and star. That is OK for one amp., but calls for attention if the high mode current is increased.
It has the usual cheap driver type with a resistor bank to limit current, as though that were necessary with those thin wires. One does not expect 7135 active current regulation chips in a $10 light.
The switch boot was off center, but that was easily fixed because it also has a neat aluminum screw in plate holding the switch, spring and (brass) spring pillar in place. Switch parts are aluminum.
There is a thin section at the front of the battery tube, ribbed to strengthen it, that must be to keep the handle from getting hot. That must be inherited from a higher current version of the design. Apparently non-flashlight people prefer that the LED be hot than that the handle be. It is becoming clear that the famous SK-68’s thin section is for this purpose.
Thanks for the feedback on this one. I've thought about picking up a 2nd one but am not sure which to buy (if any) to guarantee a solid pill.
-Garry
This driver restricts the positive side power. It appears that the controller turns on and off a transistor (FET), the output of which goes to one pad and through the resister bank to the alternate positive LED connection pad. To increase current, I moved the red LED lead from the “L1+” pad to “L+”. This increased current from about an ampere to 2.2 A, (with a fraction of an ohm in the multimeter leads).
To partly compensate for the hollow pill, I glued a (flattened) 16 mm. star to the back of the 20 mm. star. That does not improve heat transfer to the pill, but it helps heat get away from the center of the star where the LED is. Then I put heat transfer compound on the “points” of the “star” where it contacts the ledge of the pill, on the threads of the pill where it screws into the body and on the o-ring where the pill slides in the head. Now it is as bright as the light on my keychain, and it still only cost $10.
Wonder if that heatsinking will hold up to 2.2A use?
-Garry
Largely based on my experience with SS-5039s, I think there will be only small loss in efficiency. At that current, the forward voltage is still small and a significant part of the power is going out as light. A thicker plug with an interference fit to the pill would have almost compensated for the hollow pill, but that is all the power I want from this light. Hollow pill lights mostly work fairly well at the powers they are sold at, we only need to increase cooling as much as we increase power. Of course cooler is always better, but one only has so many 1962 dimes and hours to file them to fit.
I used it, mostly on middle mode, hanging from a nail, while I barbequed a top round, with the bezel ring and lens replaced by a rubbery diffuser from Fasttech. Early spring weather.