Cracked center brace

[hillegom]

I'm assuming the center brace is made of black plastic.
Take another piece of plastic, lay on top, covering the crack. Drill 4 holes, 2 on each side. Install 4 plastic screws with plastic nuts. Drill the holes the exact size of the screws. This all assumes you don't have a space between the crack, and the crack is in the middle or at least not against the edge.
Plastic screws are available, here in the lower maineland at HD