No offense, but that seems highly unlikely. The reason you can feel a 9v battery on your tongue is the dense nerve endings and the fact it's wet, plus the fact your tongue is touching both terminals. Note you can not feel the tingle when you put your fingers across the terminals, because your skin is not as sensitive as your tongue. If you could feel that with your tongue, it would mean both + and - were present at the top of the atty, which would far more likely result in a dead short and vent the batteries. I am not saying you don't know what you know, but I am saying it seems unlikely to be an electrical problem. The maximum possible voltage with 2 18650s is 8.4 volts (in the absence of converting it to AC and transforming it upward) and this really isn't enough for a human to feel. Electricity can not flow unless there is a path back to ground (the other end of the battery). If the atty was shocking you like that-- from your tongue, down your neck, out your arm and back to the hand holding the mod-- the mod would also be autofiring at the same time, and that would be a much less resistive path. The resistance factors of human tissue are such this strikes me as unlikely. I don't know what your problem is, but I suspect it lies elsewhere. That said, I only think so and might be wrong. Does the mod shock you when it's siting on the table and you touch it with your tongue without holding it in your hand? Can you post some photos of the innards?