The window glass on my 69 has staining that I cannot remove. The staining appears to be hard water residue, acid rain etching, rain-x stains or some such man made problem. The staining is difficult to see straight on but at an angle is obvious. I have tried several approach's including windex, laundry detergent, vinegar, lacquer thinner, gasoline, gunk-off, lift-off and #000 steel wool. This stuff, what ever it is, is smooth to the touch and does not seem to want to come off. Tried the search function in this section and no results. Maybe some of you guys from the harsher climes have experience or tips on how to deal with this cloudy residue ? Thanks, Brian