I just noticed that one kind of juice will plug up a carto much faster than another. When using my favorite juice, I typically need to change cartos after just 4 or 5 fills, due to it being tough to draw. A carto being used with another kind of juice will go over a week without needing to be replaced. It's the opposite of what I'd expect. The juice that plugs them up faster is PG based while the other is 100% VG, which is thicker. Could it be impurities in the PG juice? I've tried blowing them out and sucking and blowing water thru them, but once they're plugged I'm screwed. Anyone have a better method of unplugging cartos?