Many thanks for all your suggestions, the more I use SU it seems as if jiggling is a key feature of using it 😄 When I run into seemingly insurmountable problems it does take some of the fun out of it so some ocassional assistance is crucial to my SU development. Many thanks.
I got it sorted in the end by adjusting where I placed the rotation axis and then moving it into place.
when I find the way to edit or cut sections off an imported model I will be one step further. - 'edit' Got it! right click on the selection and edit component. Now we're cooking with gas..
Such is life.
Thanks for your help
teepee