Hi, I am following a tutorial for maya as I am very new to this, when I hit smooth mesh '3' everything looks good except some of the services have a random gradient which stops them from looking flat.
It doesnt happen to the whole model, just some of the components

I have attached 2 images of the before and after smooth to try and help explain it.

I have also looked at various forums/threads which have pointed to the vertex normals but I havent been able to work out how to correct as none of the suggestions for this have worked.

Any advice on how to fix this would be much appreciated so i know how to solve this if it happens again in the future.

Thanks