You can try some plain white ammonia and a toothbrush, this works pretty good and will not hurt your razor. You need the scrubbing action from the toothbrush bristles to agitate the surface a little bit, do not use any kind of power cleaner like a dremel tool, it builds up too much heat and if you use a chemical cleaner make sure it says good for brass or stainless on it, the white vinegar is a good idea too. good luck bc