This might help.
http://www.ft86club.com/forums/showt...ghlight=mirror
If that aluminum piece has stripped threads, you'll have to buy a new adapter kit. These go for around $10 I believe. It's a pretty bad design, IMHO. You screw in those "short" screws into the aluminum blank, creating the thread as you go. If you torque it just a bit too much, or if you don't apply enough pressure while you're screwing it in, you strip it.