I want to replace the ugly corroded towel bars in my otherwise nice looking bathroom. The towel bars use a set screw to lock them onto a small (3/4"x1") aluminum tab that is bonded onto the tile surface. I can't tell what was used to bond it on. It looks similar to the grout used on the walls. The house is 40 years old and as far as I can tell so are the towel bars. I would like to get the old mounting blocks off with out breaking the tiles or otherwise destroying the wall. Any suggestions?