It worked beautifully! A 30 year problem solved!! It's not often that happens.
I followed your instructions - cleared out almost all the water. Less than 1/2 a cup was left. Then I poured in your Cling N Clean. swished it around with the brush, and forgot about it. When I returned, I flushed once and the stain was completely gone. It really works!
Thank you for your help.
Paula, San Mateo CA