I don't know why, but it seems as if the juice isn't being fed in my boge. I use 3 good sized holes (2 and 1/2 turns on a COV punch), and am using a 35vg/65pg juice. My previous cartos all seemed to die a premature death with the flavor diminishing at after only about 7-8 mills of juice through it. The top of the poly fill always looks somewhat dry, and sometimes even white despite using a colored juice, so I occasionally drip some juice in there even though the juice is being fed through the tank. I do prime often as well.
