Hi and welcome to the forum, Wes Pinchot can repair, and make a new key for the locking fork. they went on the springers or truss rods forks, he is in the Chicago area, 847-259-0484.
You can also check http://www.trfindley.com/flschwinn_1...951_mdls1.html
for more info of your bike.
PS pics please.