As my website hosting is down (3 days – what a nightmare) I got my straw connector file back out. I loaded it to Shapeways and it passed! Unfortunately it was way too large. I think I had to get around the minimum size of objects in Sketchup so used inches as the unit. Apparently when exported and saved as a .stl file, you can change it to millimetres using the inch values. I used a Sketchup plugin which seemed to get the units right. My piece was giant in Shapeways and would cost over €5,300! I shrunk it in Sketchup but loads of gaps appeared on my sphere which I then spent ages plugging but going nowhere…
I think I will dig out the other way of exporting as saving and as a .stl file and see if that is quicker.