If you go the sanding, refinishing route, just a few points:

1. You will have to paint the piece, since as mentioned, polishing aluminum is rather difficult.

2. Sand the entire piece. You won't be able to match the original finish on the area you sand.

3. Use three thin coats of primer; one coat of self-etching primer and two coats of regular primer.

4. Paint it with two thin coats of spray paint. If you lay on enough that it drips, you'll be disappointed with the results.

Good luck.