Nevermind my previous note. See how it works once you get rid of the manhole. That seems to help. But if you keep losing section cuts, try moving the model to a new file.

yeah.. the contents of the zip are in there......

Thanks for coming back to me.. I like the idea of grabbing things and copying sideways. If I did this at each step and saved, I wouldn't have so many files in the project folder, as back up in case of crashes.. and it does just crash my end, when applying the quadmesh procedure. As I mentioned earlier, if I can get isocontours from a points cloud, export these to and mark up in CAD, I am still ahead of the game... Ta