To remove scratches it very easy if not deep these are thing you need.1) A drill2) Polishing compound ( Brands like Ryobi or Master Mechanic ) DO NOT APPLY METAL POLISH3) Buffing padPolishing come in different grades for different metals from Brass, steel and even for Plastic's so make sure you buy right one. SOLD AT HOME DEPOT OR LOWES AND OTHER HARDWARES Apply to pad and as you apply to drum apply even all surface scratches will be removed and a new shine will a merge. On metals like Brass or Steel you may want to apply Lacquer to maintain luster for a few years.Plastic will last as is for quite some time as is.
+1.When I worked as a die maker/engraver,I used to have to polish out molds and dies made of various metals,and to attain the right finish,you usually had to use several different grades of compound,or ***lers rouge.These compounds come in stick,cream,and liquid forms.
The only thing I would also add,is to use a different polishing pad,with each successive finer grade of polishing compound,so as to not contaminate a pad,when going from a course,to a finer grade.
Read the labels carefully,as some compounds are more aggressive,and heat sensitive than others.
Take your time,and remember that chrome plating is only a few thousandths of an inch thick.Think paper thin.Good luck.
Steve B