Hello, I recently purchased a brand new bike and after I finished riding it for the first time I washed it. I normally use Simple Green and it works beautifully but I ran out and decided to use Windex instead. But after I finished riding again some other time I noticed visible stains wear the mud was previously on the engine casing and rear swingers. I've tried to scrub out the stains but nothing worked. How can I get the stains out? Please help. Thank you