Simple x file export question (2.37a)

I’m getting a little farther with this, but as it still doesn’t work right, I’m still basically just as stumped. This is, I hope, a simplification of my earlier question.

Here are the x and blend files:

As you can see, the animation rotates the entire object. This is not what I need it to do, but at least it works – sort of. In Mesh Viewer, the middle section (that the rotation applies to) works, and the animation occurs. The rest of the object, however, doesn’t show up.

What I’ve been trying to do for about 6 days now (with no luck argh!) is separate the middle tube (with the solar panels) from the rest of the cylinder, then animate the middle section (spinning 360 degrees), while the rest stays stationary. Then I need it to export to .x with the animation and all objects intact.

I’ve tried every combination of parenting, splitting, joining, etc that I can think of. No luck.

Any advice?