Help with curved lines and shading

Is there anyone that can help with curved line shading? I'm trying to duplicate this sphere on the right with the lines that are going around the sphere. I am having problems getting the shading to follow the line around the bends. Currently I have three different color lines that I have blended. Using the blended lines does not give me a uniform thickness throughout the bends. Is there a technique to bend a line and hold the gradient shading? Any suggestions or help would be greatly appreciated.

Kind of driving off-road here, but in a difficult case like this I would make the sphere and the tube in real 3D with Blender, and thereafter would paint over missing details if any.

Xara is powerful, but realistic 3D with reflections is a totally different field.
You'll get much more quick, easy and precise results with a dedicated 3D software, that's for sure.

Keep up posted on this picture, is an interesting challenge.

This is how I would do it.

By disecting the .xar file you can see that

1/I started with a basic line

2/copied that - Ctrl+C

3/Converted the base to a shape - Menu -Arrange/Convert line to shape. Then adjusted it to fit the sphere.

4/I pasted the copied line over.

5/ Adjusted the colour of that line for the shade, repositioned it as a shadow and feathered it.

6/ Paste the copied again and adjusted it's colour for the highlights, then repositioned and feathered that.

7/ Looking at the result, I could see the "shadow line" looked unnatural, so I broke that - shape editor+B and adjusted the positions of both pieces until they fit the curve.

8/ Then I drew a shape for the shadow of the sphere on the line and put a linear transparency on that.

9/ Finally I selected all the line components and clipped them with the base line shape - Q.

Thank you for the suggestion. I never thought of using clip-view. In addition, I want to thank you for taking the time to attach a sample for me to take apart. It was very useful. I worked on the sphere for a little bit today. Here is what I accomplished so far.