I'm after some advice on this one, its starting to drive me a bit NUTS!
52/42 Chainrings. 6 speed freewheel, largest cog is 24. 1979 Campagnolo Nuovo Record RD. Sedis Chain used but not much.
I spent an hour watching and adjusting this last night but basically it seems fine on the 42 ring through 1-2 gears and its ok through 4-5-6. But it skips on 3.
Seems ok on the 52 ring through 7-8 and 10-11-12, but skips on 9, the same sprocket.
If I watch it closely, as the chain moves through the lower cage, at certain points I can see it tensioning the cage slightly (1 or 2mm), then the tension releases and the cage springs forwards. This seems to cause the skip on the sprocket. Its not easy to see every time but the chain hits the top of the teeth of the sprocket instead of engaging.
The gear cable is new and not slack but firm with the lever forwards. The chain was fitted around the 52 ring and the 24 sprocket plus one link. I've tried altering the chain tension by moving the wheel to the front and back of the dropouts which made no difference. There are no stiff links in the chain.
The jockey wheels do have wear, possibly they are causing the problem although both jockey wheels move freely.
I've been thinking about this at work all day
I'm kind of drawn back to the chain and I do have a spare so can swap it as a process of elimination.
There's not much to adjust on these derailleurs, but am I missing something?