For these kinds of probs, I have a charger that charges each individual cell directly and independently. I just wait until the lights for all cells change from red to green and its charged, all to 4.2. If a red light doesn't change to green, that cell is damaged and beyond anything but replacement which is generally not worth the time and trouble at these prices. I knew with HK lipos there would be probs and thats the reason I have this type of charger, its paid for itself saving lipos.

Not sure exactly what kind of logic a balancer uses, but chargers do just apply voltage and watch response, they have no ability to concentrate on one cell vs another. Some chargers seem to handle having a cell at 4.2 easier than others, but thats just an observation. Remember, the AC6 is a cheap charger and its intended for use on good lipos.