[Grinder] Extremely dirt | Help needed for cleaning : Coffee

Hi, all.

I have recently bought a second-hand Obel/Bregant Z10 espresso grinder, and I am cleaning It and putting new burrs.

The problem is that the inferior burrholder is extremly dirt and I don’t know how Could I clean It. It seems that is sugar(coffee/oils dirt…

Any products? Any tip?

Thanks!