I try to remember to clean all my new delivery devices before use, as you never know what might have gotten into them during manufacture.
That said, when re-assembling, make sure the head/coil is snug to the post before putting it back in the tank. I've found too that sometimes - especially if it's not snug to start with - removing the drip tip to fill can back the head off a touch. Then, especially if overfilled, but also if it goes a bit sideways in your pocket, it can / will leak down the air tube onto the battery connection.
I use Stardusts, T3, Evod, cartos, Vivi Novas, Vivi Nanos and carto tanks. In my experience, they all have their little quirks.
Whatever device you prefer, learn those quirks and how to deal with them.
