Hi Aussie. Same problem here. I'm pretty certain that one of the clutch springs have gone. Mine gets stuck in forward and reverse. I can actually see the clutch plates staying to one side. One is trying to drive one way and one the other as they are both trying to drive at once. Gunna pull mine apart and replace the springs etc and coat the axle with graphite. not oil as it'll attract the dust. I replaced the clutches about a year ago and am now kicking myself for being so stingy as not to replace the springs as well. My Evolution 2000 is now 18 years old and still goes perfectly otherwise with 800 hours on the clock. Had to "find" a starter for it though. They are no longer available. Hope this helps.
Bussy