HI Barry, I have broken the curve down to smaller arc segments to try to identify the problem area do you mind taking a screen shot of the problem end point.
Many thanks Alex.

Hi Alex,
attached drawing shows the point.
However taking WN post into consideration this converts that section into a nurbs curve not a arc.
Cheers
Barry

Many thanks for the highlight will go over the construction of this curve set another time and see if I get a clean build.
Much appreciated.
regards
Alex.