Turns out, sharpening grinder blades is easier than you think. It does take a little time and a few sheets of sandpaper, but in one evening the grinder, no matter how dull, will be good as new again. This is about the best video I've seen on the process, as it's short and straightforward. You can check out part one, but that's just the guy coloring the blade and plate with a black marker so he can track how even the surface of each is. This second video gets to the meat of the matter.