Might just be the plates have gone?
The 600SS bikes that are in the race series, mine included, have all suffered with their clutches, mainly through ham-fisted starts
A lot of them are just chucking an extra plate in, but you might want to renew them all, depending on your preference.
Get the plates out and see what they look like - if they're all blued and barely any meet on them then you'll need to replace the lot otherwise you might get away with just adding an extra one in.