The posts are designed to be a "press fit" into the hole in the Pet.They have a slight taper on the bottom of the post. They are not designed to go very far into the hole, but rather, they will stay where you press them in. If you use a slight twisting action when your press them in, they will go in easier and then lock in place as the sides of the post tighten up inside the hole.

Always use a twisting action when inserting or removing them.