Need info on metro convertible boot

Need to pick the brain of someone knowledgable with the convertible metro model.....
Just purchased a 91 convertible and don't know much about it yet.
When I put the boot on, it saggs in the rear by the trunk lip.
It seems like there should be something there holding up the center section of the hard plastic boot???..
Am I missing a part??

The boot consists of 3 pieces. Two corners and the center piece. If you only have one piece, you need the other two.

Well, depends on if you have an MK2 or an MK3 convertible. If it's an MK2, that was a bad problem with them. The washers for the hinges on the side pieces would wear out, and they would start to sag, and could no longer support the weight of the center piece. On an MK3, they solved the sagging problem by putting a plastic support piece on each of the side pieces, not the center piece. If you want, find a wrecked 92-93 metro convertible in the junkyard, and you can get those plastic support pieces for a couple bucks, and bolt them in to your car. My vert' has the worn out washers, but with the support pieces, they never sag. Also, if it's an MK2, make sure the arm that supports the side pieces hasn't ripped out of the plastic. They had a bad habit of that too.

There's one for sale on e-bay right now.