Im using the Ex arm which I actually prefer.. didnt think I would at first. But it would probably be easier to just have the old arm repaired.. it would just need some filler where the magnet area is on the arm and then repainted.. Im almost thinking of doing it myself.. Im no pro painter but I do have an art background and actually repaired my Wonder Woman PF's ear which had a small chip on the ear lobe.. looks decent. This would be more work though, the WW piece had a chip the size of a dot.
Repairing **** scares the crap out of me. Your a better man than I.