First, there's the dry hits but I managed to fix that by flipping the top seal on the post upside down so it doesn't pinch the wicks.
Second, there's the occasional (but too frequent to suit me) gurgling & leaking into the air tube. I have no idea what to do about that since everything's tightened up very well. This was before and after flipping that seal over. The wicks are thick enough to fill the slot from what I can tell, so I don't know if that could be the problem.
Third, and this is one that I can't find anyone complaining about, it's leaking out of the mouthpiece when I refill it! I've experienced this with the tube turned upside down and I've also tried it tilted to see if that helped. It didn't. The leaking is at a somewhat alarming rate. I probably get 7 or 8 drops worth of juice on my hand/lap when I refill it. It's not going down the air tube when I refill because I'm very careful about that and use a dropper with a curved tip to avoid it.
I'm especially concerned about that third problem since it seems to be uncommon. I'm concerned that there's something wrong with the air tube itself and how it connects to the tip. I don't know what I'm looking for if I'm going to fix that, though. Hopefully you guys can help me!
I've had all of these problems happen with all 3 of the coil heads (2 extras plus the one that came with the unit) so it HAS to be the tube, right?