To be honest, it sounds like the Vamo is doing exactly what it is designed to do! That's definitely a coil problem, I've seen it myself quite a few times, especially when using CE4 style clearos. Vivi Novas and ProTanks I don't recall ever having those types of issues. You have to consider, those CE4's are cheap, and in many cases considered a disposable tank... I wouldn't get too upset over it