I have a 1929 house with hardwood floors. My cat and the previous owner's cat used a section of the carpeted floor as their personal toilet. I have removed the carpeting and would like advice as to how to address the staining - not the odor - on the wood flooring short of pulling up and replacing the wood flooring planks. The area looks more like mold, blackened in nature. Any suggestions? I'm not afraid of hard work!