Oh dear. I've chosen not to see posts by DJ190 due to previous inaccuracies of his being irksome to me and actually quite dangerous in a couple of instances, however, the ignore function of the site doesn't stop re-quotes from appearing, and I see that the advice from DJ is still dodgy at best.
Firstly, please ignore the advice on identification of aluminium by using a magnet - this is utter nonsense. A magnet will only determine if there's iron in the substance you're testing, but an absence of iron doesn't mean that you have aluminium - it could easily be a copper, brass, zinc or even magnesium part (or anything else for that matter).
Secondly, it seems from the first reply that a light sanding is being advised. This will only remove the anodised finish, leaving bare aluminium which oxidises quite easily leaving a dull white-ish finish and as Depronman has said, there's also a very real danger of going through the thin layer into the substrate below (most shiny or brushed aluminium parts are only a thin deposition layer over a plastic base).
The short answer is that there's no real way of restoring the aluminium pack, short of stripping the parts out, sending them away for a new deposition layer to be applied and then re-fitting them. This technique is called metallising and is increasingly commonly used in many manufacturing industries.
I had it done to my wing mirrors a few years ago when I was trying to get the S-car mirror look and it involves spraying several layers of molten metal (usually aluminium) onto a suitable substrate, building up a layer of metal, which can then be anodised and sealed.
Sorry to be a little terse/negative, and I'm glad that the OP has quickly realised that the initial advise was to be ignored. The interchange of chrome and aluminium shows that there is a great deal of confusion on the part of someone and the use of chrome strip isn't to everyone's taste - it's a very 70's thing and quite tacky really to a lot of people, hence not seeing it much.