I have an early 80's dura-ace derailleur that I have on a road-bike I built up the past summer.
It shifts really well, however I noticed when I shift down to a lower gear on the rear cassette, the top jockey wheel start to ride the cog. However this doesn't happen when I shift up to the same cog from a lower gear.
This derailleur doesn't have a b-screw to adjust to give me more clearance either. Is this a case of a fatigued mechanism? Can this possibly be remedied by shortening the chain by one link?