I have a friend with a 990 SM that is complaining about the 2 gear "jumping"occasionally when he opens up the throttle or feathers the clutch to pop up whellies. Apparently, when he´s cruising everything is normal. What do you guys think? I´m leaning towards the gear shifting mechanism - coul be the drum with a broken wall between the tracks, or the rollers... Either way we are looking at spliting the cases, right?