Ok,

So this started for no apparent reason. Gimbal, IMU re-calibrated. All firmware is up to date. It's not the wind as it does the same thing on the ground before flight. Any thoughts?? Thanks in advanced. Please let me know if the link does not work
https://www.dropbox.com/s/148sneqf1ohk80m/Twitch.MOV?dl=0

I hope you're not using an aftermarket filter, right?  

Mark The Droner Posted at 6-29 03:49
I hope you're not using an aftermarket filter, right?

No I am not

I had the same problem intermittently about six months ago.  Sometimes there was no twitch, sometimes it would fix itself after a minute or two, but then it got worse.  Then I stopped using the aftermarket filter, said a little prayer, and it's been working perfectly ever since.  

Have you checked the four rubber dampeners at the corners of the gimbal platform?  Make sure they are properly fitted into their respective holes, and that they are not split or damaged.  Also, you should only have TWO anti-drop pins fitted, on diagonal corners.  Any more than that makes the gimbal platform too rigid and it shows up vibrations.  To me it looks like the camera platform isn't supported evenly, suggesting a damaged dampener.  With the motors off and on the ground, the image should be stable, indicating it isn't a gimbal stabilizer fault, but an unsupported shake through the airframe.

endotherm Posted at 6-29 16:53
Have you checked the four rubber dampeners at the corners of the gimbal platform?  Make sure they are properly fitted into their respective holes, and that they are not split or damaged.  Also, you should only have TWO anti-drop pins fitted, on diagonal corners.  Any more than that makes the gimbal platform too rigid and it shows up vibrations.  To me it looks like the camera platform isn't supported evenly, suggesting a damaged dampener.  With the motors off and on the ground, the image should be stable, indicating it isn't a gimbal stabilizer fault, but an unsupported shake through the airframe.

As endotherm says, have you only got TWO opposite pins in and is the picture stable when on the  ground with no motors running? If it is, start the motors and see if the image stays stable. If it gets unstable, could be a balance problem.

Hello there knotflyn. I am sorry to know that you are having issues with your DJI Phantom 3 Pro. May we know if the said drone had a hard landing or a crash before this issue happened? Thank you.