Take everything out - rear deck panel, lower seat pad, folding section - and make sure what's left is tight - side panels, RH latch, curved sections, vents, etc. Move everything, push and pull. Drive the car. Reassemble (the fun part). When you get to the rear deck panel, the metal retainer brackets go under the welded in brackets and the retaining screws (also used for the bumpers on the curved section) go thru the holes in the welded bracket into the retainers. Remember that there are rubber bumpers on the sides of the folding sections too.
That's it. Plan B is to sell the car.
Jim