the hopper is easy, simply back out the set screw and soak in a bath of Urnex or Full Circle wash. Dependent on how comfortable in dis-assembling the hopper you are,the same can be done with the hopper parts. Soak and rub down with a sponge and they should look like new. Rinse thoroughly.
I've always cleaned them as Keith described. The same urnex solution can be used to clean all the steel parts (burrs, etc.) if you feel comfortable disassembling the grinder that far. Just be aware that, if your mini is like the super jollies, some non-burr components are aluminum and soaking them in urnex will remove all the hard work Mazzer did to polish them. They'll still work the same, they'll just be considerably less pretty :).
If you're not sure how to tell the materials apart, it's best to just run some minute rice or Urnex Grindz through the burrs. It will get them sufficiently clean in most cases.
Thank you, it worked. I soaked the hopper over night. It still required some scrubbing but it is clean now. I'll try with the doser next.