My blade CX2 has a forward and backward motion (swinging, stuttering, wobbly)when flying it in a particular direction. If I am flying it forward, it will go forward, but it seems to stutter forward because it goes backward a little. It is not a smooth forward movement. It is hard to explain. But, this motion makes it harder to fly. I started to notice this after a crash. But, I have replaced everything that broke in the crash. I replaced the inner shaft with the aluminum shaft. I check every thing and every thing looks fine. Does anyone have the same problem? What could be causing this?