Dash panel lights do not have an intensity variance. They are either on at a specific rotational position or off! Crawling under the dash to inspect the switch, I noticed it was covered in white crud! As the switch mechanism is enclosed, it was difficult to completely remove the crud, so I tried to remove the switch. Pulling on the knob to slip it off didn't work nor did trying to unscrew it. I have checked my three manuals and they were no help. Anyone have an answer? I did have a little luck in increasing the intensity range by turning the knob back and forth the full range several times, hoping to scrap some of the crud off of the rheostat function.