Ok, I think that clears it up. I was confused about which detents were which, I think. As soon as I can manage to pick the lock and unchain myself from this silly desk, I'll go home and take another look at it. Then I'll dink around with the shift rods for a while and try to figure out how to screw it up and engage two gears at once. Once I understand that, the whole thing will click (hopefully).
Thanks a heap, guys!
Dan