For quite a few years now my white instrument covers have been gray and generally dingy. I've tried nearly everything I can think of in the way of cleaners. Nothing has worked. Until now. The dinginess sort of looked like mildew in the surface of the plastic, and additionally the surface was somewhat porous probably from cleaning attempts with aggressive cleaners and compounds. Here is what worked - the Clorox Bleach Pen. It took a couple of applications with a 5-10 minute wait time before rinsing with water, but the end result is a spotlessly white cover!
