Quote Originally Posted by Luke.marsh96 View Post
I think its to do with the non manifold geometry....
Well there's your problem. Do as mentioned, use netfabb to sort out the problem.

Asking a printer to print a non manifold object is like asking you to draw a 3 dimensional object on paper and have it work in 3 dimensions (Or better, draw/create a 4 dimensional cube, and I don't mean the shadow of one, but an actual one). There are extra surfaces that shouldn't exist according to the slicer, it's like adding an extra spacial dimension to the object.