Finding surface connectivity defects
Click
(Geometry tab > Modify panel > Surface > Surface Connectivity Diagnostic).The Surface Connectivity Diagnostic dialog appears.
Select whether you want the diagnostic to find free edges and/or non-manifold edges, then click Show to run the diagnostic.
Note: If any connectivity problems are identified, you can either correct them in the original CAD program used to create the geometry file, or use 
(Geometry tab > Modify panel > Surface > Edit Surface Ties).