Hello all, I am still a rookie with this stuff. I have a Apollo Lava Tube. About 2 weeks ago I got a Vision Nova tank. I had an issue a few times where suddenly I couldn't get any draw at all - nothing it is like no air was coming through. I would unscrew the tank, rescrew it in and it would work again. Last night, I changed out the head (or Cartomizer - whatever the name for the piece is that has the wick in that screws in). And now I can't get any draw at all. It is like it is sealed. I thought maybe I had a bed head/cartomizer - so I put in another one and same thing - no draw at all. My Tube works fine on the drip tip, so it is not the tube. I really liked the tank though, anyone have any ideas for a total newbie on messing around to get this to work?