Many thanks, guys -
That tracing over is a good suggestion, though I haven't learned when doing a polyline with arcs how to make the arc change direction, as when drawing an ogee (reversing) curve made up of two arcs. Unless I can control the direction of the new arc segment, that won't help.
To John R, I understand what you mean by "not touching," having had years of Autocad and Corel Draw experience.
But both of those packages allowed for joining in such cases.
(On my screen, by the way, under fairly good magnification, I can't see the non-joints.)
In Turbocad, doesn't either "meet two lines" or "shrink/extend line" cause line segments to join? My problem is that in only about one out of every 100 tries, do either of those commands work. Sometimes, I can get them to work by closing the drawing and software, and starting fresh.
What is distressing is that if these join-related commands work, shouldn't they work a second time within the same session?