Are there weights I can use for the challenger? Cleaned my tile today using the tile brush and glads. Tiles look great and cleaned up much easier than using a shark steam mop. But the grouts lines still look bad.
Any kind of runners weights with velcro connectors will enable you to add weight to your machine. I carry a 20-lb. piece around with me, and wrap it around the lower end of the shaft when cleaning T & G. For grout lines that still don't look as good as you might like, there's a brush on a hinge, into which you insert a broom handle that screws in, which will let you take a 2nd shot at gray grout lines. A steam vapor machine will do the same thing, using the smallest brush attachment. The broomstick brush can be ordered, for $17, at the Magic Wand Company (www.maginwandcompany.com) (If you simply Google "magic wand" you will probably be directed to another company - Hitachi - which sells a massager intended for women's pleasure.) Not sure if this would work on grout lines.
Not all grout lines are able to be returned to their original bright shade. Often mold has grown in the grout lines, permanently darkening them. You would have to be able to sand or otherwise abrade away the top surface of the grout line to reach the original color if mold has done its damage. Although I've never tried it, the small sanding burr attachment of a Dremel tool might be able to do this, although it could be tedious work.