Can you apply grease to the steering rack if it seems stiff or should you just have it rebuilt?

Is it stiff with the front end off the ground? If so, my next step would be to detach the tie rods and test again (isolate the problem as the rack not ball joints or tie rod links). As to what you can do to free up the rack, I'm blissfully un-experienced in that category, but also interested in the answer.

Is this a new occurrence? I've found cars where the rack mounts have been tweaked after even a minor incident. When one side of the rack mount was loosened the rack freed up. Straightening the mount (or changing the # of shims on one side used to adjust bump steer) cleared up the problem.

As Greg noted, check the intervening ball joints. You should be able to freely twist the rod ends on either end attached to the rack. I've seen situations where someone has made a toe adjustment and in tightening the rod ends did not center them properly to provide enough play. Also check for any bent pieces; the rack end that attached to the ball joint is susceptible to being tweaked and as it's hard to see, this can be missed during repairs.

Appreciate the above replies. After disconnecting all links, it looks like a bent steering shaft (new car for us). Will update if I find anything else. Thanks again