How do we replace that black piece and the spring? On the previous video, those pieces are still in place. Ours is broken, so I can manually lift up the piece that stops it from standing upright (as shown in the video), but I would like to fix it for good so I don't have to do that all the time. I believe the pieces I need are 90019989 and 90122303, but I have no idea how to get to them. Any help would be greatly appreciated! Thanks in advance.