Hello there,
As you can see on the textured image the numpad keys aren’t shaded as the same as the other.
Any ideas ?
Thanks.
@7rHash_tag Might try checking normals and doubles. With everything selected in edit mode try recalculating normals (Ctrl+N) also you might also remove any possible doubles as well while you are in edit mode and everything selected as well using shortcut key ( W ) remove doubles.
Hi,
You were right, there were the same meshes oververlaping each other.
I don’t know why, I couldn’t get rid of them with the “remove doubles” function (0 vertices removed) so I just removed all of them with B -> X -> Vertices.
Thank you 
No problem, glad it helped.