jrjr2u,

Thanks for the feedback on the gasket sealer. I just want to make sure I don't have any leaks when I re-assemble. I've seen some really resiliant sealer on McCullogh chainsaw engines so I figured that might be the way to go. Let us know that permatex number when you find it.

The best way to make the aluminum bright again will be an mechanical / abrasive polishing. The surface oxidation of the aluminum won't be removed chemically without further etching the underlying aluminum. I would recommend a buffing wheel on your drill or bench grinder and a tube of Flitz or other wheel polish. Of course once it's polished you'd have to seal the surface to prevent it from oxidizing again.
I'll polish up a case this afternoon and post some pics to demonstrate.

If this were a ferrous metal I'd use a product called Evapo-Rust to remove the oxide but even then a mechanical polish would still be necessary to make it shine.