So my first notch coil was getting a tad junky. Time for my first rewick! Took it all apart, pulled the old cotton which did look gunky, but the notch coil was all clean! Nothing to even dry burn.
Had to play with the cotton to get it right. It needs to be fairly tight in there, and I was using a strip from a Japanese cotton pad that already had the outer layers pulled. My first attempt was too thin, so the coil was loose in the cartridge (whatever you call the coil holding assembly). Doubled it up, and had to fiddle around again to make sure the notch was centered and both edges were touching metal. Took a few tries before I lost the "no atomizer" display on my mod and finally got a resistance reading.
Put everything back together, filled it, and no leaking (so far, it's only been a half hour). Got a few nice little bubbles out the juice holes that always make you feel better that you have a proper seal, and my coil life has been extended. I feel better about this tank with this outcome. It's actually a nice complement for my Pico when I'm out as it is small and discreet. It also holds more than say my Serpent mini which is only good for ~2ml and not enough for a full day without a refill. This holds ~3.5 ml in real life conditions, which I guess is close to the spec of 4 ml.