I have never "Cleaned" the grinder...I know you can put some rice through it but it doesn't seem to need it. I have taken off the container and gave that a wash a few times but that's it.
The machine, I live in an area where the water is really soft so I have ZERO limescale in it which i am amazed with.
One of the benefits of living in Scotland! I bought my Classic second hand from the south of England so it needed a run through with descaler, but it's been perfect since then.