in a previous car I sorted a drive issue by opening up and cleaning the optical laser reader and a good clean of all sliding components.
So when the wifes sat nav packed up not reading the disc I was hopeful.
Having got into it, I have found a metal disc obviously part of the locating mechanism from the centre of the drive loose and laying on the laser reader. This photo is the way it was laying looking down, so it must go on the top or bottom of the centre locating part...I do not know which, also how it was fixed.....there are no other loose parts in the unit.
I have a photo of itDSCN1873.jpg