My last Riva died about a week ago and I was in no financial shape to replace it. Thankfully the wonderful PIF group helped me out. Today in the mail was a 3.7 box mod and some cartos, thank you lox. I'm having a problem with it though and I'm hoping someone here can help. When i try and vape there is zero airflow. Feels like trying to suck solid ice cream through a straw. I've tried loosening it and that didn't work. The only way to get air flow is to just sit the carto on the connection. Once you turn it even once it gets no airflow. I've also tried raising the center post on the carto and on the mod but it didn't help either. The last thing I tried was filing the little notches on the side of the carto with a nail file. That didn't work either. This is a 901 connection and I've tried 3 different cartos. The cartos I tried were all the same kind. I don't have anything different to try with it. If anyone has any suggestion that might work I'd really appreciate hearing it. I'd like a solution that is free since I'm broke. I can post some pics if that will help. Just let me know.Thanks!