Shading issues appear when I change an object from Shade Flat to Shade Smooth. One end of the cables turned out beautifully. The other end looks like it is missing faces, which it is not. I began with a cylinder. I then extruded and scaled and inset the object as needed to create the shape. Save for the two round faces on the end, all the faces are quads. Normals are correct. Moved the light. I have scoured the internet all day looking for someone with a similar issue and tried those fixes, but nothing seems to work.
New users are not permitted to attach files. If you reply with an email, I can send you the blend file.
Here are photos of what is looks like.