https://www.mcmaster.com/products/ci...ining-rings~~/
these are not easy to remove, and i've seen them used on campy parts before... most likely a 2 turn version... the trick is having a pick to get behind the end, once it's located... then keeping the end you started at from once again finding it's way back into the groove....
try this on a tiny piston wrist pin in a weed eater engine some time.
i recommended a new Short block, mostly
the hub you're dealing with will be worlds easier to sort out, i'd hope.

it may also be a plain spring wire type... the first step is finding the gap between the two ends of those... once again, a pick set is called for...that funny shaped one with the angles in it is your savior.... usually... the 90* one works sometimes too... and the straight awl pick can come in handy to find the ends, or get behind the partially removed ring...

and, there's a possibility that Campy Re-invented the wheel again... or hub, in this case... sigh.