Hi Barry, can you post the .obj file? And maybe also the modified ImportObj script you're using too?

One guess is maybe the issue is if you have n-gons in the mesh. You might see if you can process any n-gons in Blender into triangles before making the .obj file out from Blender.

Note that it's generally not advisable to convert a dense polygon mesh file into CAD as an individual trimmed surface for every separate poly face like the ImportObj script is doing. That's why it's not part of the default import options.

- Michael