Pivo.ai (https://pivo.ai/) 360 auto tracking for sport is a high quality and useful video tracker that my wife is using for her equestrian lessons.
Unfortunately her Pivo (previous version, not sold anymore) has broken at some time and the upper cap of the Pivo was detached from the motor part. But that's not even it, there were 2 parts that was doing the connection between the motorized rotor and the upper cap to make it move. These two parts were a cylinder with crants on the upper side which was matching the crants in the cap, and to make sure this cylinder was in connection with the cap, a spring was pushing it enough on the cap.
The long story finish by saying that we lost the two internal parts, the cylinder and the spring ...
As Pivo is not selling separated parts for the older version, we had two options, buy a new one for about 150€ or try to solve the issue.

Well, it might not be perfect, but at least for us it worked, the cylinder doesn't even need the spring anymore and fits in the rotor spin and seems to be correctly fitting in the cap. The Pivo is back alive !

It worth trying to print it if you were in the same situation as us.
Now, the cranks on the top are not rigid enough in PLA, but if you glue the side of the cylinder on the side with the cap, it won't move.
You need also to glue inside the bottow of the cylinder on the spin of the rotor so that this will make sure the rotor is spinning the cylinder which therefore will turn the cap.

I don't have images of the final 3D printed object, due to the fact that we wanted to solve the issue quickly. Sorry for that !

The 3D design was simply made-up based on what I could observe and shaped using TinkerCad.