OK ..... please try this :
The black hex screw has been found on mine and another guy I know P3 to be incorrectly set. Basically the screw was tightened but the gimbal arm was not correctly seated. It allowed the camera and gimbal arm to move. The motors then were activating to keep all in line ...
Once loosened, arm seated firmly, onto the seat not the gimbal board above it, and screw tightened properly - both mine and other guys then were quiet and all worked perfectly.
The same mount is on Std as well as Pro / Adv.
Photo shows the screw and seat .... the screw is a common 1.5mm hex size.
Let us know if this helps ....
Nigel