Take the keycap off and pull the stabiliser stems up and down with your hands. Is there any jamming when you do this? If so, you might consider modifying the stem of the stabilisers. This helps to stop jamming and generally makes the stabilisers feel nicer :
cherry stabilizers are more sensitive to warped spacebars.
Your space bar is likely warped.
Get a new space bar.Show Image(http://www.freesmileys.org/emoticons/tuzki-bunnys/tuzki-bunny-emoticon-021.gif)