Update. I managed to get this sorted. I managed to get a long flat bladed screwdriver into the slot where the "wing" snapped off. Prior to this I tapped around it with the screwdriver and a hammer to break the rust seal and added some oil. Then it was a matter of inserting the flat blade of the screwdriver into the slot and turning it. It took a lot of pressure on the screwdriver to get it to turn but it did turn.
Here is the offending article and what I replaced it with. Hopefully this might help someone in the future.
Bookmarks