hmmmm...I don't remember what the "glass" portion looked like when I disassembled the mirror years ago. I know the colored plastic "fairing" snaps off. Then the glass is attached through the black plastic housing with some sort of pin or something. This allows the mirror to rotate back/forth and up/down. Not much help...but I don't think a flat piece of mirror will work. Technically, the outer edge is ground at a different angle to provide a "wide" (albeit blurry) view. Your best bet may be to source a mirror with good glass and crappy/broken plastic and use it as a parts donor.