I fear dizzlebizzle may have left us, but I have just replaced the cogwheel in my MMI for a brass one due it it snapping in half.
Having seen this thread I thought I would test before too far into reinstallation, and it is exactly the same. So for anyone else doing this, it is a common issue.

The walnut cover clips on a curved metal cover and this has a rack of teeth along each edge that engage with a pinion bu.t it is not possible to change the position of this easily as I would have to jump a few teeth and they are tight meshing. I only replaced the motor cog, so not sure how it got out of sync.

Not sure if this is useful or not?

MMi Cog Replacement to Screen Mechanism

Thanks Architex_mA8tey - what great instructions, much better than the ones I used. I have sorted the issue out and all back together. +++

Glad it helped +++
I've added it to the stickies in the relevant section plus the tech dump so it's there for anyone else