Re: problem with chandelier arm....need advice
As brass is a copper/zinc alloy I would be careful using a chemical that would dissolve copper.
Connect a vacuum to one end of the arm we'll call that end "A" and feed a heavy thread into the other end Called "B". If the vacuum can pull the thread through disconnect the vac and start pulling the thread through end "A", as you do wrap it around the wire end at end "B". After you have several turns around the wire hold the the end "B" taught and pull on end "A". With the thread wrapped around the wire and held taught with a little luck you will pull the wire out.
Be sure you live your life, because you are a long time dead.-Scottish Proverb