I think I'll start lubing them up with some 100% VG that I have here. Sorry for the tight fits. I just don't want these things to leak past the o-rings. They do get a little easier to pull apart after a few refills. If you are going to use the bottom fill method, PLEASE don't pry on the colored bottom cap with anything. This material is tough, but is a lot more brittle then delrin. I found this out the hard way and I have no way of replacing these as they are all one of a kind.
ORC, it sounds to me like you got juice in the airway. Once the carto is full, slide it up past the slot and vape it for a while. I do this, and when I get an off taste, I slide it back down to re-saturate the filler. Once the filler gets super saturated, that's when it will try to leak down the batt. connector. If you get a gurgling, that's a good clue to slide the tank up a bit and close the hole off. You can use this to kind of control the flow of liquid also. Just partially expose the hole.