Stylus for Intuos 3 sticks sometimes

My Stylus seems to be sticking in some manner so that sometimes it takes off by itself and leaves a trail and sometimes I have to give it a positive touch to complete a lasso movement. It also seems to be unable to move smoothly when I attempt to scroll with it and again, to stop the scroll I have to press down with it to bring the scroll to a stop.
I have tried removing the nib and replacing it but that doesn't seem to work. I even exchanged it with a nib from another pen (not the pen for the Intuos) and that didn't seem to work either.
Is it the pen or ??? Anyone who can help I would appreciate an answer. Wacom didn't give me much support when I asked them.