I think I found the problem. Look at the pics, that spring tab to release the blad is laying against the metal on the blade. I bent the arm a bit, and the problem seems to be gone.
Seems like the latch is missing, its at the end away from hinge side. A little pick and a pry and it would come off. Think my 65 barracuda should be similar,will check. If i can find them that is..