I have used the rug doctor cleaning solution in my Bissell Pro Heat carpet cleaner, and where I have rested the machine to change direction I have been left with yellow stains (the cleaning solution is yellow). The stains have obviously been caused by the cleaning solution, any suggestions on how to get rid of them. I've tried a few spot cleaners but with no effect. Desperate as carpet is only a couple of years old and light beige in colour. thanks in advance