Mine has the same parts. On mine that part is part of the bottom cover and cannot be taken out. You can use the year and model on Boats.net to find the parts use the search feature.I would try to epoxy it cut ditch with dremal fill with epoxy clamp closed with small C clamps. When cured usually 48 hrs remove clamps sand flat apply a good lube then give it a shot.
On mine I would have to replace the whole bottom cowling (for lack of better term) and that is not easy. Shame MG does not give maint. instructions to lube it every year or so.
Who ever said nothing in life is impossible.
Never tried slamming a revolving door.