I use the "drip & flick" method that Rocket uses. I also put a wood toothpick into the center air hole to prevent juice from getting into it while I'm priming. The filler has to end up looking like a wet slushy drink when fully primed. Saturated but not pooling on top. Look up my cartotank tutorial in my Blog Entries by clicking the link under my avatar.
I've found dual coils often get a burnt taste. My reasoning is the top coil will end up burning the filler because it lies above the wick holes on the carto. Switch to single coil cartos and you won't get the burnt taste.
I've found dual coils often get a burnt taste. My reasoning is the top coil will end up burning the filler because it lies above the wick holes on the carto. Switch to single coil cartos and you won't get the burnt taste.