Originally Posted by
illdthedj
it definitely has play right at the pivot bolt where it attaches to the hanger...even when the bolt is tight, and the b-screw is properly above that little tab on the hanger.
im guessing its just a super used rear derailleur and just needs replacing
I've cured upper pivot slop on both Campy and Shimano derailers, by disassembling the pivot and inserting a washer. Had to mess around with the washer a bit, filing it thinner and maybe putting a notch in the side IIRC, but it worked a treat.
The pivot was a little stiff afterwards, but since it wasn't too stiff to respond it worked fine.