Baird,
One of the primary problems of the old standard Campy brakes is that they need to have the pivots overhauled periodically to work properly. It is easy to check by undoing the spring from the catch on the arms and seeing if the arms move freely without play. I find it fairly common that the lubrication has dried up and makes these arms stiff to move. Triflow spray can be the lazy or hurried mans fix but taking them apart, lubing and reassembling is not all that difficult. I'm also suspicious that your cables are greatly adding to the problem and Dale already suggested that fix.
Doug Fattic
Niles, Michigan