The top edge is held at the back of the top by the wide plastic bow that goes all along the back of the top. It looks like the bow is held on by a couple of screws at each end.
The sides of the bottom are held here (left side shown):
The long plastic piece at the back pushes up into a clip at either end at the back of the top cavity. The intention is that water run off of it into the foam catch trays.
Note the routing of the two top hold-down cables thru a loop on each side (left side shown):
Threaded Mode
