I find if one wacks the taper receiver, i.e. steering arm, (in the case of ball joints, the spindle) so as to "distort the taper" it helps (hitting on the side, if the taper is up and down ) this works extreamly well if one has an "air chisel" using a blunt round punch.
then using the blunt punch on the end of the threaded shaft, I like to keep the nut on as it kinda keeps the air punch centered ,also it keeps it from hitting you or "things" when it comes loose.
later, ol'George