Back the bolt out a few turns and whack it like the book shows until the bolt is loose - you should be able to move it up and down by hand very easily - indicating that the expander plug is all the way clear of the bottom of the stem. Don't worry about over-loosening as long as you only go a few turns at a time between strikes with the hammer. Once the expander bolt is loose, you should be able to move the stem. I say "should" because sometimes the stem is simply stuck, but this is a different can of worms. Get the expander plug free (use some penetrating oil if needed) as a first step.