I finally found an easy and affective way to bring old stained plastic back to life. I tried sanding and soda blasting but was never happy. I used the green Scotch-Brite pad with Lacquer thinner. I would dip the pad in the thinner and scrub. It will evaporate quickly, after about 10 seconds. I would repeat about 3 times then use a paper towel with thinner to clean the grime and pad dust off. Then I would repeat again, scrubbing with the pad and thinner, then finish off with a paper towel and thinner. Then I used a quality lacquer clear coat. It worked great!! The thinner does not eat the plastic, but is strong enough to lift the stains out. The Scotch-Brite wet sanding will not round the edges off either. The trick is to use only Lacquer thinner.... (not paint thinner....could be mineral spirits). I did this cover section in 5 minutes.