We've done it two ways. The shiniest results came from the stout mag wheel cleaner that bobs409 and Dean are talking about - Eagle was the brand, for non-coated wheels. We did take the case apart, but I guess you could put it on with a brush and avoid eating the internals. The problem was, after enough soak time to really clean the case, it was a very dull and dark gray color.
So then we took it over to the wire wheel, and it removed the dull gray and left a very bright aluminum finish. Went to a finer wheel, then used a mag wheel polish to seal. Looks pretty sharp! (its the one you can see in my avatar).
The other solution was taking it to the local starter/alternator shop, and they disassembled, put in new bearings & brushes, bead blasted the case, and even put a shiny new fan and pulley on, all for $30 including parts & labor! It looks factory-fresh.
SSOW
