As Doogie mentioned, its impossible to reguvenate the Copper Vein back to its original state AFTER it's tarnished with patina. I seen a thread about this topic before I got mine and immediately used some Rustoleum Clear Enamel on it to help seal the paint finish.
Your REO Grand just needs a new paint job.

You can sand it down to bare metal with 600grit sandpaper. And then
buy some Copper Vein or Hammertone paint from Lowes to repaint it. Afterwords, be sure to put a clear coat on it to seal it.
This is what I'm going to do if I ever have to. Hope it works for you. If you do give her new paint, take pics before and after. There are some threads in which folks are repainting their Grands, and they've done some beautiful work.