Hi, I recently installed an H3-3D gimbal in my FC40. I also upgraded to a GoPro Hero 4 black edition. Without any counterbalance the gimbal is not quite balanced - it drops down slightly on the right when not powered up. I followed the general suggestion of using coins on the motor to balance the gimbal. I found that a single 1p coin was enough to get it to remain horizontal when not powered on. However, when powered on it gets a lot of vibration feedback. It doesn't seem right that when supposedly balanced it causes vibration, whereas without being balanced there is no noise at all. The interesting thing is that it wasn't balanced properly even with my old GoPro Hero 3 silver. I thought that was the camera the gimbal was designed for? Either way - does it matter too much if it isn't perfectly balanced if it works OK when in operation? I haven't actually had a chance to use it yet because of weather so I'll have to find that out in the future. I did see people talking about IMU calibration, however I don't see any option for that in the Gimbal Assistant - in fact the only thing I get is a slider showing the pitch position and an option to upgrade (which I did for the IMU). I hope someone can help. Thanks.