After removing the required number of spacers, I scored the steerer tube. Then put the pipe cutter in place, 3mm below the scored line.
Had to remove the stem in order to be able to rotate the pipe cutter.
Took the fork out (carefully placing the headset parts on a sheet, so as to not lose their order). Then, knock in a new star fangled nut. I use an old screwdriver in the hole, but there are great dies for it. Also, when hammering it, I support the fork in my hand under the crown. That way, you are not risking hammering when the forks are braced against the ground!