Hello Dingley,
there are several posts on the forum that cover the silver arches and how best to keep them clean, BUT and there is always a but....
It depends on what state they are in because not only are they a prat to keep good, they also are affected by corrosion from under the lacquer, so without pictures it's hard to answer or give a definitive reply because you could be talking about corrosion and we could be advising about splotches etc...
Have a delve into the best forum for the RCZ, you will find many answers to many questions.
And remember, we aren't just here for the faults, we like to see other RCZ's and what peeps are doing with them, we also have meets, next year for example is the tenth year anniversary of the great Z and much is a foot for a day to remember...... and we want as many RCZ's as we can muster, so tell your mate / your next door neighbour / your dentist and dare I say it - your hairdresser.... we want you all - LOL!!!!