My Vision Plus had developed a very unstable gimbal problem.  DJI paid to have it shipped, first to Miamiand then to California, twice, but the problem persisted.  They had left some test footage on the cardand sure enough, it was working perfectly.

Contacted Adam Andrews at Aeroworks, sent some video, withina few minutes, he said that it was a switch on my smart phone.    My drone is fixed.  

Adam Andrews should be on a retainer for DJI.  

I am guessing you had FPV ticked on your phone, or something similar ?
So your phantom was not fixed, it never had a problem in the first place...

Well, what switch?  Why keep it a secret?

Yes, it was the FPV switch.  

Its in the settings of the App, "enable FPV mode", when its on the camera fixes in place, like the standard vision camera, this gives a proper FPV experience, when you turn it off the camera goes into stable mode and you get smooth video footage.