Thank you. That almost did it. See the attached image. All of the lines are showing now except for that bottom one. The object is at least now useable.
I played with the status codes (which I really don't understand) and found that if I used 2+4 then it shows that bottom line, but it also shows all of the lines that come from the 'segmented' poly cut (instead of being round it makes a number of small straight cuts). So that doesn't work.
I don't believe I can 'draw' a line in there in the elevations view so do you have any suggestions on this last little line?
Thanks so much - I can now use the object.