Need a return spring, I believe most of the campag ones from that era ere the same. i.e Nouvo Record, Gran Sport, triomphe etc....Mine squeaks like hell which I believe is because it is out of shape. I have tried to correct it but to no avail.
Have you tried greasing it? also if it is squeaking against the lug where it secures on the calliper arm you can slide a little PTFE sleeve over the end of the spring...
Colnago Super, C record Delta 7v,
Olagnero Signature Model, DA 7401
Battaglin EL101 tubing 8v
Wilier Campagnolo 8v Record
Daccordi Furioso, Campag Veloce 9v