Hi all,
I've seen other threads suggesting this as well. I've had the same issue with the gimbal 'flopping', but it has since corrected itself (in my brief flight test) by simply making sure the wires did not put any pressure on the gimbal. The wire that I had to change was the bulky HDMI wire. I basically rerouted it around the outside of the gimbal as much as possible, and would suggest you try the same. It may be necessary to access from below the battery.
A useful video to remove the battery tray is here:
Good luck!