yeh those ones are nortorious. You'll need to find replacement parts or replacement frame depending on how severe the damage is. I've got a pair that's semi-broken and can be used as replacement frame. Those spring hinges give up the ghost quickly... and one of my hinges lost its springiness, thus the 'semi broken'
If you do find replacement parts you have to make doubly sure it'd work for your frame as I recall there were a few variations of square wire around that time