vacuum

Hi guys. So im pretty experienced with wicking. But i cant get my dumptank too work properly. I think its a vacuum issue as i saw yesterday 3 airflow holes had bubbles coming out and flavor was amazing. Now after 1 day without touching anything inside there it only comes air bubbles out of 1...

Having issues with my new Melo 3 mini. With a new coil in it it vapes great, loads of flavor and big clouds. After I refill it gets maybe 4 puffs and then the flavor goes away. I find that by unscrewing the fill cap the favor returns for about 4 puffs. Somehow the tank appears to be vacuum...