2004 F150 Power steering acting up

[Alagnak]

Sorry if this is already in here- I tried searching but I've never had much luck with the site's search engine. My power steering is acting a little goofy. It's tough to turn when you first try, but then eases up but won't 'rebound'/auto steer back to center, you have to pull it back fairly hard. Fluid appears good, normal level (changed it out two years ago when I replaced a line). PS pump sounds fine. I did a little digging around on interwebz about greasing the u-joints on the steering shaft. That didn't seem to do much. Thanks for any info.

[fishing tech]

Lower column shaft has a small ujoint that seizes up.

[JOHNBIGDOG]

2nd the intermediate shaft. Its the part that can bee seen under the hood, it has two U Joints in it. They rust up causing the hard/soft feel you describe.

[Jeremy airjer W]

Fairly common on Nissan sedans as well.