Sounds like the cams need to be reset. Cam position can be a confusing aspect of the rudder mechanisim for first timers. (How it works is pretty un-obvious.)
I found an easy way to reset the cams (so hooks are pointing up) that does not involve marring the cams or detent plungers with a screw-driver, or loosening the cam adjuster screws:
Using a piece of 1/4" line, create a loop on one end, and the tie the other end to a hammer. Wrap the loop around the "hook" of the cam. Swing the hammer with just enough force to rotate the cam to the up position. Works like a charm. Now when you follow Matt's rudder down/lock procedure, the cam will toggle down locking the two castings together, securing the rudder.
2002 H17 Sport/SE