wrote:
I'm in the process of restoring my '72 Bob Jackson. I have a set of
Cinelli Campione del Mondo #66 bars, and a set of Campy Record brake
levers. The lever mounts are very difficult to install over the ends
of the bars - I haven't used the 3 pound mallet yet, and I haven't
gotten the mounts to slip onto the bars yet either :-)

Are there possibly different size mounts for these vintage levers?
snip

Not different size clamps, but different size bars are a distinct
possibility. Cinelli bars are slightly larger in diameter than other
bars of similar vintage- if the levers had been mounted on bars of
slightly smaller diameter, it could be that the clamp is distorted
enough to prevent it from sliding onto the bars.

The clamp and screw is removable from the lever. Undo the bolt
completely and see if you can slip it on the bar by itself. If not, you
can expand it and round it out from the inside using a pair of heavy
pliers in reverse- push them in and expand the clamp outward. Once
you've got the clamp in position, reassemble the lever in place.
It should fit- it's just tight.

Jeff