The star is held in by a spring into its larger holder which is held in my a flat place with a big and small hole inside the grill. You need to remove the inner plate by sliding the securing plate sideways then comes the fun part of prying the spring into position and you most likely also have to remove the old part by prying that spring out.

Good luck, I only did it once and it took about an hour to get the spring right but then again I just despise springs of any kind.

Pete