I just put together a cross bike using most of the 1999 Chorus 9-speed hardware from my old Pinarello. The exception is the crankset which is an FSA 46/36 compact setup.
Everything is pretty sweet apart from the rear derailleur which seems to have a fair amount of lateral play. I shortened the chain, adjusted the limit screws and dialled in the indexing so it shifts fine going down from small (13t) to big (23t) cog, but on the way back up (from big cog to small) the rear derailleur slightly over-shifts and the chain rubs on the next cog down (e.g. when shifting from the 16t to the 15t, the chain will start rubbing on the 14t.) A small push on the shift-lever (i.e. not enough to shift back down to the 16t) will fine-tune the derailleur so it stops rubbing, so I can work around the problem, but I still don't like the fact that it's happening...
My question is whether:
1. this can be fixed (maybe by adjusting tension somewhere in the derailleur, replacing a spring etc...)
2. it's normal (although I never noticed it on the 53/39 crankset on the Pinarello) or
3. the deraillleur is worn out and needs to be replaced (unlikely imho)
Thanks for reading.