If you can't get them to budge any other way and you have a good die grinder, you might try cutting the cap off and removing the ball and stud, then grind a groove down into the side of the pressed in piece . . . not quite into the wall of the control arm, but really, really close. That will relieve most of the pressure of the interferance fit and it should pop right out without heat. After I cut through mine with a hack saw, they almost fell out with some light taps of a small ball peen hammer.
Those suckers are TIGHT and the walls are thick . . . and if they were like mine, had been in there for about 35 years and had gotten used to their home and didn't want to leave. I drove my new ones in with a three pound hammer . . . it took about 40 bazzillion swings to get all 4 of 'em in. I couldn't lift my arm for a month. I've pressed a lot of automotive parts in and out but I have never seen anything on a passinger vehicle with that tight of a pressed in fit.
And again, DO NOT lock a press down on them and THEN apply the heat . . . if the turn loose all at once while they are under tons of pressure, they are equivilent to a small cannon ball. Someone could die. Put just enough pressure to hold them in place, Heat them, THEN slowly apply more pressure.
