You can remove the top of my Zanussi cooker (different model) as follows. It's hooked on at the front and held down with two screws at the back. These go through black plastic pads and require a T10 security bit (star with a central hole). There are also four tiny screws around the largest burner. These are extremely difficult to get out due to heat and corrosion. Once the screws are out, lift up the lid at the back and push slightly forward.
Cookerman
July 2010