Yes it's a plastic arm in the middle of the cover hinge (one on each side). See that post I linked. There is a photo there showing the broken plastic with the arrows. Not that On either side of the hinge, there are plastic "ears" that can be rotated toward the front or back of the car. For normal use, they should be rotate to the rear. When you are servicing the system, they are rotated toward the front, which puts tension on the plastic arm inside the hinge so that it will keep the top cover open.