you shouldn�t polish to the point you remove a lot of material thus making the lock losser then it already is .Simply look for any burr�s . those you can remove . The rest you want to smooth out .
This means that sometimes scratches have to stay but that�s ok , as long as you don�t have sharp edges.
Fine diamond plates work well for polishing , so does real fine emery. In some cases just a rag with lith liberal use of brasso will help enormously

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