I received a nice Campy NR FD, and noticed that the cage was really hard to move. I thought the pivots were gummed up and just needed a good oiling (as has been the case on several old RD's that I've had). However, working in light oil into the pivots didn't loosen them up.
Two out of three pivots can be disassembled: the one which holds the return spring unscrews from the cage, and the other pivot on the derailleur body slides off after removing a circlip. Upon inspection, those two pivots are just fine, not at all gummed up. The non-serviceable pivot point below, which connects the pivot arm to the cage by means of a rivet, was found to be the culprit:
This pivot takes a lot of force to move, so much so that it counters the return spring's action to the point where the RD can't reliably return to rest by spring action alone (the spring seems very strong). No amount of oiling has loosened it up. It feels like it's binding. What's causing it and how can I remedy it?