Mrecoolgar is correct (I think, to the best of my foggy memory).
Don't be surprised if you have to invent a new way to fasten it back up.
It used to be held with a push on circular ring with teeth in the inside diameter that looks something like the pressure plate fingers in your clutch system; but miniature.
The blank circular stud / post that hangs down from the dash goes through a hole in your cover and the push on ring is forced on the stud and all the little teeth dig into the stud when you come to a stop, and the teeth are bent facing down. Now the little fingers are pointing down (like they were dragged on), and when you pry on the push-on clip to remove it, the teeth straighten out and reverse to pointing up, often severing the stud.
You can get down on the floor with a tiny awl or screw driver and bend the teeth individually to get the push-on circular ring off, but no one does that.
I would look into drilling a tiny pilot hole in the stud base and finding a self tapper with a big washer to hold the thing in place.
Or, if the stud is still there, go to a place that sells cir-clips (for metal shafting) and get an external cir-clip that you can install with the help of cir-clip pliers (with the pins sticking out the ends).
