MMI screen cogs replaced..... no more horrible clicking noise now
 

I appreciate many of you will have already performed this fix and it's not the most difficult job, but........
After 2 or 3 months of the common broken cogs, I finally got round to replacing the cogs with brass ones.
Alas, it now operates exactly as it should - hurrah!
However, when reinstalling all the dash items, I hit 2 snags:
1. The cable to the connector of the coin box will not release enough to connect. I'm sure it will be much easier when the glovebox is removed, but, for now there's no illumination on it - which I can live with.
2. The centre air vents ......the electronic controller in the dash doesn't align with the mechanical controller on the actual vent. Somehow, the electrical controller needs to moved to a new position to allow the air vents to be pushed fully 'home', without damaging any parts.

Any ideas on item 2?

Yes!
When I bought my A8, the coinholder never lit up, so I piggy backed the connector on the vent to make it light up. Years later, I removed the glovebox and there was the cable and connector, someone must have dropped it down before i bought it. Yours must have dropped and got snagged.

The vents just need removing and reinstalling. Plug in the electrical connector and set the thumbwheel back and forth until the peg in the dash is in the middle. Then put the Y shaped thing on top of the vent into the middle of it's travel and slide the vent back in carefully - it engages 9 times out of 10.