Hi Dave,

The outer loop was made with the insert edge loop tool and in the inner loop was an extrue to create the supporting edge in the same way it was done through most of the model so far.

I have tried recreating the same component and got a similar issue, although this time when i turned off the 2 sided lighting most of the component went black with grey patches, reversing the normals on that made it grey with black patches.

cheers