If salt got on your bindings from cartop ski racks you have nobody to blame but yourself. All the major manufactures sold binding covers for protecting bindings during transport. This is just one example of the binding protection available in the 1970's. Never had a spring issue with any binding, but had lots of Salomon Plastic issues and they never had a recall.Most of the springs in the heels of older bindings are cracked due to stress and exposure to salt.
(Cartop ski carriers)
Don't be surprised when the spring suddenly collapses and you get spit out.
I have several sets of old Looks in my attic and they all have cracked springs in the heels.