ive noticed in the 15 or so times that ive pulled linkages off transmissions that they tend to stick onto the shift rod that enters the trans. so it might actually be possible that the pin is out, and the forward/reverse motion is causing the shifter rod to move, but when u go to the 1st/2nd or 5th/reverse slots, the linkage just spins. if nothing else, drop a damn bolt in there till you can get a new pin, but i think autoway honda stocks em....

otherwise, i hope that is the problem you find. cuz if the pin IS in there, you have a bigger prob on your hands....