CA, I used 0.2 layer with 5 top layers, 3 bottom and 40% infill. The attached photo shows that the print has a clear seam, that passes light thru it ( thats how I noticed it). I already printed mine with my first printer ( da Vinci Jr ) and there was no issue. Also, Cura will have no issues.
Effector-S3D.jpg

fred, That's a lottta work to try to get this stl working. Like I said earlier, I just printed it for a life size mode to do some design work. If I need another, I'll just slice in Cura. It sounds like the origin of the issue is the way the part was stitched together, but I do not know how to do it any better.