My 79 has the same lock minus the key to be able to lock it.
Fix would be
A buy a replacement lock.
B replace the glovebox door with one from my stash.
C replace glovebox door with the 8/80+ style glovebox door.
Think I'll go with option C. Current style adjusted so it doesn't rattle is a pain to open from the driver's seat. Twist style makes this easier. Do not keep anything worth stealing inside the glovebox. With a lock thief might think there is something worth stealing and cause damage breaking in.