I forget the name brand, but I have several of the kind that are blue where yours is red. The big rubber plunger at the end of the shaft swells and gets tight on the the outer tubing. they are hard to get out once they get tight. i have a couple of mine that are tight right now and i am dreading having to change them. usually have to put vise grips on them and beat them all the way out.

Scott Hanners