No need to apologize 
but i appreciate it anyway.
I’d blame the thickness before the centering, but they both matter. Is there any jiggle /slop to the switch?
A click is a click is a click. By that I mean if it’s clicking then it should be switching. So I suspect that you are looking at a contact issue elsewhere. However, I used an o-ring that I just happen to have hanging around so I didn’t measure it but it fit with just a little bit of play and it definitely sat up proud of the rubber piece that it’s sitting in. The idea of moving the tail cap or switch to different lights should prove everything.
So, how about this?
https://www.amazon.com/008-Neoprene-Ring-Durometer-Round/dp/B0053UU1KG
008 Neoprene O-Ring, 70A Durometer, Round, Black, 3/16” ID, 5/16” OD, 1/16” Width (Pack of 100)
Is that the right size?
Verdict: the problem follows the PCB. I swapped the PCB from the FW3T to the FW3C and the problem followed the PCB to the FW3T. I did not swap the retaining ring (per the above, only the FW3T had a retaining ring: I kept that retaining ring in the FW3T after the swap).
So, what can I do?
Here are some more photos showing which PCB was in which torch originally (before the swap).
I emailed Neal to see if he has spare parts, but I haven’t heard back yet. Any ideas on where to get spare FW3A parts without buying a whole light?
Remove the poppers and inspect under them. To me it seems like the troubled one isn’t touching the center pad reliably. You could put a tiny solder blob on the center pcb pad and likely clear this up. Make sure the popper is taped on nice and centered and there is no debris or flux splatter on any of the contacts or popper. Wiping down with a cotton swab and ipa then deoxit if you have any could help too.
So when is a click not a click? When the clicker is dirty or burned or otherwise fudged up. When you open it please take some good pictures with good lighting before you start cleaning.
What’s the best way to open it up?
Mine is just held down with the kapton tape. Just lift one side. But before you do that I would manipulate the switch with a ballpoint pen or other sharp object and then again with a flat metal ruler on it’s side or something with the o-ring in place to see if it’s going straight down. An o-ring that can’t get off center probably is a better choice.
Thanks.
https://www.amazon.com/008-Neoprene-Ring-Durometer-Round/dp/B0053UU1KG(link is external)
008 Neoprene O-Ring, 70A Durometer, Round, Black, 3/16” ID, 5/16” OD, 1/16” Width (Pack of 100)
Is that the right size?
Yes
I use 2 washers with glue. Is little more hard clicky but less wobble
If I open it up and end up needing a replacement, any ideas on where to get spare FW3A parts without buying a whole light?
I would also consider buying a whole light and getting an extra tail cap PCB for a few bucks extra.
I don’t think anything is going to need replaced. Slight tweaking should fix this
Here it is opened up. Looks clean to me.
There actually are some splatter/ spot marks of some kind on there in the ‘bullseye’ position of the pcb. The electronics cleaner is fine but rubbing alcohol on a cotton swab + elbow grease is better. Clean both the underside of the popper in a twisting or ‘lapping’ motion with the swabs and ensure before reassembly that there arent any cotton fibers hanging around under there.
After I clean it with alcohol, should I apply a film of anything? Or just leave it completely bare?
Clean and dry.
Cleaned it with 99.9% and replaced the o-ring with the 008 size. Light is happy and so am I.
A big THANK YOU to all!