Originally Posted by GreyDawggg
Yes if you never saw any leaks from the cables or anywhere the chances are very likely that your slave cylinder o-ring has called it a day. If it were me I would pull the slave cylinder off and check it out, replace the o-ring with a good viton o-ring and bleed the system with some new mineral fluid. You bleed it from the bottom up. It's like bleeding brakes you need a syringe with 6mm id tube to go over the little nipple and as you crack it you slowly push the new oil through. You might have to do it a few times to get all the air out (I did) and you can see little bubbles escaping the top reservoir. It is good to have someone help you.
I agree, change the o-ring in the slave. For bleeding, I used a syringe and clear vinyl hose to bleed from the bottom up as GreyDawgg suggests. Once you are done that, give it a few pumps, then, while holding the clutch lever in, just crack the bleed nipple on the slave slightly, and you will probably find one last bubble hanging out in the slave, at least I did.