I'll try that, William. One thing I'm currently doing is getting my backup frameset ready for flight (adding an FPV camera to it etc.) I plan to fly it just with landing gear and using the same FC settings as the primary frameset to get a baseline for the amount of vibration, and then fly it with the gimbal to see how it behaves. If, as I suspect, there is much less vibration, then I'm going to start systematically swapping out motors on the primary frameset to weed out the "bad" ones. I'll try doing some flights with a 3-axis accelerometer on board that can get a decent sample rate so that I can see what frequencies are in the vibration. I keep thinking that knowing that information will help me figure out where the vibration is coming from. I've still not ruled out the Yaw PID controller -- but I'm confront with the apparent contradiction that I don't remember seeing this level of vibration two months ago, just recently -- so something, somewhere has changed..... Andy.