Hi Ronald,
model was loaded and evaluated in Rhino...

But for your is a good chance too see isolines (not tested) in Moi3D with this script.....
http://moi3d.com/forum/index.php?webtag=MOI&msg=6841.3

and unclosed edge with this script from here:
SelectNakedEdgesV2 – it deselects all objects and highlight all edges that are not joined so that can help to show you what parts of an object are the ones stopping it from being a closed solid (watertight object).
http://kyticka.webzdarma.cz/3d/moi/