I am trying to remove single handle from kohler K-R648.(Water is oozing from handle.) I have removed set screw, but handle will not come off. I don't want to force too hard and break something. Any suggestions

I suggested a handle puller at first before realizing that it wouldn't work. The splines are corroded. Load it up with W-40 and try again. Work it back and forth as you pull up. Good luck, mTom