An update on my trials and tribulations... and perhaps the solution that may help others.
I had a well working coil/wick (SS wick) using bottom airflow per BJ43. Vaped it solely for over a week, was absolutely loving it. The coil was getting gunked and vapor was dropping off, so I thought, "Well, we've had success... re-coil it and get some practice!"
Well, first issue, I accidentally dropped my wick and it bounced into a little bit of used motor oil. So, had to make a new wick.
I've been fighting with this thing ever since; I must have gotten really lucky on my original wick & coil.
No shorts that I can tell... fresh coil burns nice and even. Fill it up with juice and prime wick... hardly any vapor, and frequent dry or metallic hits. Take off the mouthpiece and burn, and it seems to be generating a fair amount of vapor and the coil looks really good (no hot spots that I can see). I can can even see juice bubbling up the wick.
I tried a tighter coil... I tried looser... one layer of cig paper... two layers of cig paper.... new wicks in different configurations (smaller center hole, larger center hole, less mesh, more mesh). Every time, even coil but a good hit here and there but otherwise nasty, and barely any vapor when drawing (but what was there had a harsh TH).
At wits end, I gave the small hole drilled in the side next to the wick a try... what the heck, can't hurt. I used a #60 drill bit (smallest I had). Screwed the tank all the way down on my Provari, which completely closes the bottom air.
Wow... right away, *MUCH* more vapor, a little less TH (although still pronounced compared to the carto tank I had to resort to), and the flavor is just brilliant... clean and bright. This is the same coil/wick that was generating nasty hits just before this, and the difference is drastic.
I've only been vaping the new setup for 5 minutes, and so far so good, but I'll vape it tomorrow through the day and report back my findings.