I have no idea why or how this happens but I have tried everything from using polyfill which stinks farnkly and also using now blue foam. It seems like on some atomizers I dont have this issue of where if my cart is half full I get no vapor so I have to top it off constantly. Is there anyway to fix this? It seems to be doing the same thing on both atomizers and I have tried a new cartridge and it didnt make any difference.