Hi Barry,

re:
> allocated the script to a key (Add curve.changeClosedCurveSeam( new_start_parameter, rebuild_circles /*optional, default = true */ ); )
> but could not get it to work.

That's not a complete script, it's one fragment that needs a location for the new seam point.

I've attached a plug-in command that lets you pick a point and then calls that function to modify the seam to that point.

- Michael

EDIT: 2/1/2021 - fixed bug with clicking on clines or axis lines or on intersections between a curve and a cline/axis line.