Custom Posts: menu postioning

I have 5 or 6 different custom posts on a WP website. I tried ordering them 5, 6, 7, 8, 9 etc, but then I noticed that the Media tab was above the last 1 or 2 post types.

So I tried setting the menu_position property to ‘5’ on all custom posts. This did not make any difference unfortunately, it seems like the Media tab just wants to sit there in front of the last couple of post types!

Does anybody know a way I can shift the media tab down a bit?

Thanks