I was trying to adjust my headset today and while it was loose accidentally bumped the front wheel. Everything shifted upward and when I looked down I noticed a large O-ring that I hadn't seen before. I've looked at instruction manuals and everything and can't figure out where this goes. I see no grooves that it will fit in and when I put it in between the top cap and frame as pictured the head set doesn't move smoothly. Where does it go?