There is a small retaining clip (nut) that holds the furnace cover in place. See the bottom of the photo below. It's the kind that you turn it with a screwdriver to "fatten" the clips behind and keep the cover in place. Mine just broke in two. I don't even know what this kind of clip is called ... so I cannot figure out how to look up a replacement. Does anyone know what these clips are and/or where I can get a replacement? Thanks.