Did you try to turn the tube by 180 degrees (clip end of the tube to the head of the light)?
Good question. Never noticed the different knurling, as it is not so pronounced in real life than on the photo. But it makes sense as the tail cap has a bit different anodizing than the body tube. I received the light like this. Maybe the tailcap is from a different unit, switched at the factory.
I have one more thing. Does your light have the small ridge between the clip groove and the O ring?
Yes. The head can be screwed in only halfway 
No, my Astrolux does not have this ridge. But I would like to have one to prevent slipping of the clip onto the threads during battery change.
Interesting. I have never seen it in any review pictures either.
I came across a similar problem in the head of one of the original A6 anodized lights. The threading in the head for the retaining ring was not cut far enough into the head for the retaining ring to press against the driver and resulted in a weak driver ground with only spring pressure creating contact. Since I couldn’t change the threads I soldered two shims to the driver for good contact. To fix the gap just sand the end of the tube until you are satisfied with the looks. Don’t go too far or that lip will act as a stop before contact is made.
It might also just be a cocked switch pcb.
Will try sanding the end of the body tube, thanks for the suggestion.
Known issue. The driver tends to reset under very high load. Specifically, at the end of a full-power FET pulse, the FET closes so fast that it creates a ripple effect, and if the amps and voltage were high enough, it can make the driver reboot. It’s being fixed in future BLF driver designs, but that’s totally unrelated to what Banggood sells.
Mine is the same. Kind of disappointing. The front piece is a slightly smaller diameter than the rest of the body and I can’t swap some of the bare parts with anodized parts due to different threading. QC issues like this are one of the big reasons people have been unhappy with Manker.
Can anyone recommend a good soldering iron for a newbie. I want to try doing some of the basic mods in this post.
Thanks,
Caleb
A Hakko or one of the clones. The one I bought had a cold joint inside the wand and fixing that was the last time I used my old 20w Weller. The variable temp and different tips take care of all my basic needs. Hot air reflow would be nice to have but if you don’t assemble boards it’s not necessary. There are several threads on this topic.
Is it similar on the short tubes (fitting the early BLF A6) on the head-side. The slot for the O-Ring is too wide and the part with the bigger diameter ,on the opposite side to the thread, is too small. Thats why the O-Ring is only half covered.
Does it close if you remove the oring? If it does then look for a thinner oring, if it doesn’t then file or sand shorter the battery tube until you like the fit. Another of the inconsistencies was depth of switch pcb seat and battery tube stop.
No, it’s the same without the O-ring.
Btw, on my Astrolux the switch protrudes a little from the button guards too. Probably the PCB seat variation you said…
If you do choose to sand the tube shorter remove the orings, place some 220 wet or dry sanpaper on a flat, smooth work surface( a piece of 2x6 or plywood will do), and sand then rotate, sand then rotate. This helps to keep it even though evenness isn’t essential. Stop before you go too far and wrap the tube with some tape to protect it, all it takes is one slip and the tube will tip onto the knurling mid stroke and ruin the deal. It’s not difficult, merely tedious and if you take measures to protect the tube from accidents it should go fine. A sheet of 220 costs about a buck.
Thank you. I will try
Updating my debugging posts for non functional BLF A6 from Banggood over pages 24 and 25 - after some back and forth Banggood sent me a new head unit and that promptly fixed things. Not sure if it’s the same tint as the original order but not a big issue - now have two fully functional A6s…
And a Nitefighter…
And whatever I buy next from Bangood…
Thanks for all the debugging help.
Hi bought a BLF A6 and attempted the bypass spring mod and removed the spring off the tailcap. I tried solidering it back but ending up getting solider everywhere and now the light will not turn on. Is there anyway to fix this or to purchase a replacement tailcap?
Thanks
Replacement switches can be obtained from several sources, including the US-based MtnElectronics.com if you want it quickly. I don’t recall if banggood offers the switches by themselves yet.