I just spent 20 minutes or so getting all the kief out of my grinder. I took the following steps:
First off, if you have a cheap 20 dollar grinder instead of a solid name brand, you can expect metal flakes or whatever else impurities your kief. This is where the ? you get what you pay for? comes into play.
First I used a paperclip to scrape as much easily recoverable kief from edges, the rifling where the pieces screw together, teeth, etc.
Next I got a new tooth brush and brushed that bitch down. The screen, the teeth area, anywhere kief can get caked up.
I had this grinder for a few months now, this is what I recovered using these steps.