Removing the back from a Belling Format 636 Oven?

I need to remove the back from a belling Format 636 Oven to replace the fan oven element. When all the screws have been removed and the back plate is unattached, there is a cylindrical protrudance through the backplate that prevents it from being removed. This cylindrical protrudance is near the top, just right of centre. How do I proceed, is there a way of removing the cylindrical obstruction ?