You will have to polish them back,use a tin of "BRASSO" or similar metal polish on a clean lint free cloth(an old tshirt)and polish in a circular motion a bit at a time-it will take a long time-,do a small section first,clean it off with a clean rag and see how it goes,when it is all done wash lightly with warm soapy water.When applying it change to a fresh piece of material fairly often.You can also use toothpaste to do it.It's all about patience unfortunately,easy to damage but slow to repair,you will be happy to see it all clear again though,take your time you don't need to do it all at once.
Rich
February 2008