Vents not controllable

[AndyMason]

Hi all, hope someone can please advise?

In our 2012 (third gen, I believe) Rav4, the vents no longer seem to 'do as they're told' based on the heating controls. The air temperature coming out of them is correct, as is the fan strength, but I can't control which vents the air comes out - it seems fixed on the windscreen, nothing from the face or feet vents, which isn't ideal in winter.

I don't know names of the parts, but apparently there's a 'disc' right at the back of the console that can come loose or disengage, and don't know if it's that that's gone. How easy/difficult a job is it to replace it, if that's the case? (I assume it's not straightforward!)

Many thanks!

  Andy.