I have a white vinyl top and I use Blue Magic Convertible Top Cleaner that I found at autozone. I follow the instructions correctly and I clean my top everytime that I wash my car (every 1 to 2 weeks) and there is a spot that looks like dust and I can not seem to get it out. Should I try a different vertible top cleaner to try and get this out or what? BTW the top isn't very old probably 6-7 months old.