Acetone works extremely well for cleaning things. However, keep it away from paint! Brake fluid is even worse for paint. When you remove the slider cover make sure you tap UP on the bottom of the panel to free it. Don't pull out or such - get a piece of wood or such and hammer straight up on the ends of the panel alternating from front to rear a bit at a time (naturally after you removed the two screws).

Tom

'79 Mercedes 300SD "Green Hornet"
'84 Westy Vanagon "Spiny Norman"
'86 Alfa Romeo Spider "Dinsdale"
'98 Mercedes E320 wagon "Silver Hornet"