Hi all,
I've found this method on a french website and I decided to post it here, since I've tested it and it works (very) well!!
So your alu grinder begins to be dirty, the filter does not let pass the trichromes anymore...etc
Put some milk (the fatter the better; cream works well) and your desassembled grinder in a pan, and heat it, 'til it simmers and try to keep it simmering all long, avoiding the milk to boil as it destroys THC.
You can brush it with a new toothbrush, to accelerate the process, but wait a minimum of an hour to be sure it's gone in the fat!
Keep in mind that the mixture will be strong enought for 2/4 persons so be careful especially if it's been a while since you've not cleaned your grinder!
Sorry I'm not sure of my english!
Peace