I think this is what shapeways sent me back when they fixed it. change filename extension to fixed.stl and check it out yourself with shapeways. but should be good.On page 5 you said you updated your shapeways link with the new file.
Searching thread for shapeways and tinkercad, I cannot find it.
Any chance you have either link in your browser history. And could spare the time to re-share.