I cleaned mine a couple of months ago but should have replaced it. The switch is about $25.
You need to start with removing the ashtray. You will find 2 screws at the bottom of the opening. DO NOT DROP the screws. Or you might have to take out the console
Next remove radio. If you still have the original there will be two spring clips on the bottom of the radio at the outer edges. Push them up while pulling out the radio. You got 3 hands
You should now be able to get to the 2 screws that hold the switch panel in place at the bottom. Pull the panel out at the bottom then down a little and it should come out far enough to get to the back of the switch. Push at the sides on the back of the switch and it should come out.
The switch can be opened by prying as the sides of the rocker portion. I do not remember if there were springs inside or not. You will find grease where the rocker rubs and the contacts chared and pitted from 15 years of arcing.
Clean them if you want to but I will be replacing mine before the rainy seasons comes to Florida. I was back to pressing the switch a couple of times to get it to work only a week of use after cleaning them.
It will only take you about 1 hour if you DO NOT DROP screws.
old blue is your 500 blue? Mine is and has faded to a shade I like better than original but having a hard time finding touch up paint. Has yours faded?