The kneading blade should just slide straight up easily.
It appears yours may not have been out for a while and has just got stuck.
You may need to get some pliers and over a soft but thick cloth, clamp on the kneading blade (hold the gear under the drum with your other hand) and jiggle and pull up with the pliers. You may damage the surface of the blade a bit, but you can get replacements ones.
Brian R
July 2008