TIG,
I checked and found I'd somehow put LibFredo6.rb in the LIBFREDO6_Dir_45 folder. I pulled it back into Plugins and now everything works a treat. Thanks for your help.
Tim
The example SKP did indeed have custom axes.
To reset to the model-axes place the cursor over an visible axis line and right-click and use 'reset'.
Then draw the line parallel to the red axis and a unconnected curve, orient the group and make the bend...
You know... from your description I thought you wanted to keep the top part to be able to show or hide it in camera shots. If you just want lower shelving, that back support can also be modified by selecting the edges at the top and moving them downward, aligning with the blue axis... (since all the sides are exactly vertical).