That will be a worn shifter sheet, I have had the same thing a couple of times.
Take the gator off
compress the little spring clip that holds on the rubber boot
slide the rubber boot up the stick
then where the stick goes push the out side ring down and turn it and it should pop out
then you can take the stick out
look down the hole and you will see your shift sheet witch is a round ring and the two shaft align the shafts up so the cut outs are level use a big screw driver
you can pop the shifter sheet out and you will proberly need a replacement as its worn.,
or for a better explanation look here
http://zukioffroad.com/Tech_Library/tcase_shifter_bushing.htmSome time you can get away with cleaning it up and greasing it but I think there are only a few quid so you may aswell buy a new one.