[phinnaeus]

Why are you supposing that the two halves of the coupler are moving apart? They are both attached to the moving section

[beambot]

Figure 9 implies that the coupler drives the blue gear (shaft of lead screw).

But let's assume you are right: Then how does the blue gear at top of the lead screw simultaneously turn the shaft and move upwards too?

[Linosaurus]

I believe that everything in figure nine moves together vertically except the yellow/orange ball screw nut and pink horizontal thingie, these are fixed to the satellite.

The sensor and stabilizer on the right side are flexible.

[formerly_proven]

https://www.youtube.com/watch?v=5MxH1sfJLBQ