Frame damage on silver alloy frames.

[howierart]

My moutain bike is about ten years old and alloy with a silver finish. However in places especially near to where cables run the finish is starting to look scruffy, chipped and tarnished. Can someone please advise me on reversing this process and cleaning up the frame back to an as new finish. Do I need any special products laquer etc - what is recommended.

The attached picture ilustrates the damage to the top tube.

Thanks.