This weekend I started to screw one of my Pro tank 3s onto one of my Ego Twists. It acted as if the threads on one or the other had been completely stripped, as if there were NO threads. I tried the battery on another PT3 and it worked just fine. I then tried another PT3 on the original battery and it worked just fine. It seemed that this particular battery/tank combination just didn't work. Unfortunately, I don't have numbers on my batteries to know exactly which battery was causing the problem or which tank it wouldn't screw onto. I numbered my batteries after that and hit the same combination this morning. I haven't been able to find any reference on ECF that addressed this particular peculiarity. Has anyone else run into this?