Don't stuff the chamber full of cotton. It's leaking because you do use too much cotton. This is an old issue that we talked about months a go. If you do use too much cotton and the cotton touches the posts than it's going to leak the juice from the posts to the base.
Just enuogh cotton to cover the juice holes is more than enough. Cut the cotton at the lenght of the base and put your coil in an angle like shown in the picture to make the legs shorter and you can put your cotton easily sideways to the juice holes.
I'm putting my coil 3-5 mm from the airflow hole. I'm uisng an 8 wraps Kanthal 27 AWG around 2.5mm coil and vape it at 9-12 Watt. I'm using the 1.2 mm AFC insert (the second smallest and I think it's the one that was preinstalled). I'm using 50/50 juices.
I hope this helps and if it's still leaking check your O-rings.
Edited on 5/31/2019 at 2:50 AM. Reason: