had the same problem - everything replaced - still does not lock....well, it locks but if you shove the TG in pretty hard, it releases. Also, dealer just traded my rusting (underside hinges)
out tonneau cover with one of a used truck that was in better shape and you know what? The key from my original tonneau cover lock fits the lock from the replacement. I guess one key will unlock every tonneau cover, so if you have a tc lock key, your will open everyone elses.