Alrighty then! Here's an update:
I disassembled the WH. Swabbed out with rubbing alcohol. Didn't see anything out of the ordinary. No lint, no nothing.
Hmmm, thought let's try the KFL on my back-up. Put it on my itty bitty Simplicity 18350 and guess what? Hot battery!! (Maybe Snork has something there with the atty short idea?).
Got home. Checked with a meter. Yep, short. Tightened the moving building platform (can't think of term) re-built, and its vaping like a champ. I guess the fact that the KFL worked perfectly the other night on a ProVari (after heating up the batteries in the WH) added to my confusion. Provaris are pretty finicky with their toppers even when all is well with the topper.
Soooooooo.....perhaps this is the end of this drama. What a long, strange trip it's been. Must say, I've been humbled. I've been using the KFL for months without issue (except for dropping it and causing a leak due to the threads getting crossed). I actually was feeling a tad bit cocky with all of my luck with this topper!
Guess, the moral of the story is that there is always more to learn. Hoping this is my last "learning opportunity" for the next day or 2.
. And yes, always have a back-up! Love this filly.!