When I was fitting the back window into the plane, I found the backup metal didn't fit correctly. So, this afternoon, I redid it. There has got to be an easier way. But, here is how I did it.
I cut an oversize piece of metal to fit behind the plexiglass. I drilled the holes through the holes already in the plexiglass and clecoed it into place.
Dang that sounds simple. But, I still ended up having to cut the pieces into two sections. AGH!