Are you talking where ball joint stud goes into the spindle? DO NOT hit it with or without the nut on it. Use a BMFH and hit the spindle where stud goes through
Just smack it right where the tapered stud goes through. If that doesn’t work, heat as much as you can without burning the rubber, then cool quickly with ice water.. Do it several times. Hitting with Big Mutha F Hammer after cooling. Maybe try heating medium then hitting while hot