Here's the grinder in quite dirty conditions.
First step is to unplug the funnel which is held by two magnets:
Afterwards you loosen the screw which helds the whole body:
Here's the whole body upside down:
Take off the adjustment screw:
Now you can take out the lower burr, its carrier and the spring:
When you reassemble the whole grinder check wether the lower burr is moving easily up an down. This is crucial for an easy adjustment of the fineness of grinding.