I'm in the middle of putting the boot on my automatic, but can't figure out how to get the knob back on. I've got the main knob, the button to push in to change gears, and the spring that flew out when we pulled the knob off. Where does the spring go, and how does the button stay in place? I can't see any way of it locking itself. I know I'm missing something stupid, so help me out.