I suspect that calibrating the drone upside down helps no more than praying. I can imagine how this works: the weight of the camera shifts the gimbal and jamming disappears. But the opposite can also happen. In my drone, I threw away the yaw motor cap. He clung to the flexible cable. This detail is of no use. The drone protects the yaw motor with its dimensions.
P4 Gimbal Yaw Problem
The upside down does help once in a while but not often. Not sure why. I have a lot of yaw motor drums. When someone throws theirs away I can try mine and I have always found one that works.
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