If you think it's rust, try a Mr. Clean Magic Eraser. If you think it may be metals, then try crushing up a few vitamin C tablets, put them in a sock, or some ph down in a sock, and rub them on the stain. This will take off any metal stains. I have found that rust doesn't respond as well to the vitamin C or ph down - but the eraser works wonders! Hope this helps, let us know