Thanks to Mr_P for the following. This is the first time I have seen this simple alignment fix.
Keep the C2 button on the rear of the controller pressed, and at the same time turn the right hand wheel. A grid will be displayed and at the same time the gimbal will tilt as you turn the wheel.
I put a small table in front of the camera to establish the horizontal plane.
View attachment 86576
Below, the table edge is horizontal. Release the C2 button and the gimbal will be horizontally aligned.
View attachment 86578