In order of ease/cost: Clean the plates and basket Check stack height and adjust with steel plates of different thickness check for notches in the hub and basket Replace the clutch pack Replace the basket and hub -
You could put another dished steel plate in the clutch, this is how I've cured a couple of them now. Plus it's less 'graunchy' when pulling away with a smoother take up.
Smear grease on all the friction surfaces, wipe off excess, bake in oven at 200c until smoke clears. Job done