I just did it:

My MK4 was starting to die



Take the cover off

Unscrew 4 torx bolts and remove flatcable



And another cable pull off

And there you have your complete laser unit

I searched for a brandnew DVD M3 4.6

Brandnew one for €145 bought at http://www.navigatie-onderdelen.nl/
New vs old:

Place it back.


Cables back


4 torx bolts screw

The cover back on


And your MK4 is back new again. Since then he is much faster and no reading errors anymore.