I think it's absolutely fantastic to hear that someone else is having trouble with chocolate or coffee (or really any flavor) in the Protank, burnt hits after just a few puffs. This is virtually the only thread I could find where the issue just could not be solved and wasn't related to having a crappy brand juice or too high of voltage. With my systems however, I'm not finding a solution with multiple delivery devices - I've tried 2.5, 2.8, and 3.0 (different ohms for different devices) and air flow controllers. I already tried many things with the Protank, removing the rubber gasket, removing a flavor wick, but it all led to instant leaking, before any judgements about flavor could be made, because I do use thin juice that is supposed to at least work a couple days by major brands that I try before I buy.