So I was about to put my chain back on my Ron Cooper all Campy Nuovo Record bike after cleaning it, when I discovered to my horror that the tension pulley on the Nuovo Record rear derailleur had cracked. Then I remembered that I had removed the pulley from an old broken Simplex plastic rear derailleur that came with a Mercier 100 that I bought and restored as a single speed. Despite being two totally different manufacturers from different countries, The Simplex pulley is a perfect match in diameter, width and bore for the Campy pulley. I'm sure glad I kept it instead of just throwing it away with the broken Simplex derailleur.