I once had gearbox oil tipped all over mine (standard clutch)because someone mistook the plug at the top for somewhere to put it... Soaked the clutch, it slipped badlly for about 10 mins and absolutely OK there after... My clutch cable is set so it's about 1/4 inch off the "touching the bearing point", and I've added a spring to hold it off for the bearing's sake, it'll outlast the clutch anyway.
Are you sure it's not the wheels spinning, specially possible with foot down in 3rd on wet road! :-P
I recon, as a longshot, might be worth check that the crank doesn't move in and out, check at the pulley end, Just in case
the centre thrust bearing dissapeared. V unlikely, but worth 2 second check...