Just revisiting this… I know it’s like 2.5 years old, but I thought I’d add a little of my experience here.
First, the very early FW3A flashlights had no retaining ring in the tail cap. They did this probably for cost savings on manufacture. But it created a tragic vulnerability. Most people are used to taking off the tail cap to get to the battery. And when you do that, the loose parts can get jostled, or even fall out. Putting it back together is a delicate matter and can result in some things out of alignment, causing the switch not to work properly.
The 2nd production run (and all others going forward) introduced the tail cap inner retaining ring, which eliminated that particular vulnerability, but… it didn’t solve the other problem–the inner connecting tube. You really shouldn’t ever need to disassemble the tail cap. It sounds to me like you had the inner tube connectivity fault, and by disassembling the tail cap there’s either a misalignment or a missing part.
The design fault of the FW3A, as I see it, is that the distance between the connecting ring on the mcpcb is very close to the metal retaining rings. It’s so narrow that if enough conductive debris builds up inside it, there ends up being a short. Also, upon periodic battery changes, if the tube isn’t treated super carefully, some of the anodizing can get worn off along the edges… which will guarantee a short.
My early FW3A shorted out only once, years ago, and hasn’t since I made sure to thoroughly clean the contact rings and the inner tube. And I always replace the battery from the front.
A 2nd production FW3A I own that I decided to convert to 18350 then 18500 has been problematic. As 18350, it was infuriatingly unreliable upon reassembling after a battery change. I’d have to fiddle with it a lot to get it back to working again. It nearly suffered a battery explosion when it shorted out unattended. Thankfully I got to it in time.
I had tried TWO different 18350 tubes and both were problematic, so my last attempt was an 18500 tube. That has been more reliable. However, I have to clean the inner contact points periodically or else it suffers shorts.
The FW3A is an historic flashlight, the first most widely successful implementation of Anduril. But, it has been surpassed. Lumintop made no effort to fix the original problem, except to release a side switch version that solved this issue, the EDC18. I have to believe FW3A sales have dropped off significantly. Even the top of the line LM10 inventory hasn’t been depleted and is frequently offered at super discount prices. It’s sad that it came to this.
