Pop the clutch cover off and look at the basket. You shouldn't have to remove any clutch parts to visually inspect it. If it looks grooved, then I would remove the basket and file the grooves.
I -THINK- a grooved clutch basket will make a clutch grabby. As in there is no middle ground, just on or off actuation. At least a friends 250 displayed these symptoms. It was a very annoying clutch to use and it could not be feathered at all.
I could set my clutch to allow the bike to start in 1st gear without shooting out from under you, but on top end the clutch would slip. Can't have that! So I had mine set for maximum grab on top end which unfortunately made it almost impossible to start in gear.
I would look at the basket. If it's grooved then definitely file and polish the edges smooth again. Also, if you install some stiffer clutch springs you might be able to get the clutch adjusted a little further out so that it will hold nice and tight on the top end while allowing 1st gear start up.
However, these are all just temporary fixes because once you start to groove up the basket again it will probably start to display it's old characteristics.
I too raced hare scrambles on mine and watched the pack pull away on the line while I had to start and then drop in gear. Sucks.
Micah