+1 my lower pulley had huge gouges worn into the tops of the teeth. When I replaced it this problem was greatly reduced, though it still occurs a little bit. I suspect my narrow 8-speed chain, since it doesn't have the protruding rivet heads on each link plate. (This is with a Cyclone Mk II GT rear mech, 7-speed Hyperglide cassette hub, and KMC X 8-speed chain.)