I've been a good Rover DIY guy, but the fates are still not favoring me. See if you can diagnose this ...

'03 Discovery 2. 110k.
Here is the chronological order of events
*Steering gradually began binding, to the point that in certain conditions it would lock-up-tight and refuse to recover from a left hand turn. If you really yanked on it, you could get is straighten out, but with a loud POP like you were breaking the steering loose from something on which it was caught.
* One day the power steering pump blew a seal and leaked out all over the driveway. I replaced the pump and the overflow tank and the refill hose.
* The binding continued.
*I lubed everything I could get to without tearing down the steering assembly. No change.
* Found that the ends/ball joints on the track rod and drag link were torn up. Replaced all. This minimized the binding, but did not eliminate it.
* Replaced the steering dampener. No change.
* Replaced the upper and lower ball joints on the wheel hub, on both sides. No change.
* Replaced the CV joints and axles on both sides. No change.
* Replaced the lower steering column. No change.
* Tinkered with the adjuster on the top of the steering box. No change.
* Bled the power steering box multiple times.

What I now have is a steering issue where it does not really bind, but suffers from multiple sticky, then mushy or "hollow" spots as you drive. It is driveable, but not what it should be.

The only piece I have yet to replace, save the steering box, is the high pressure line. I've got one ready to go. Really hoping someone knows of a demon that lives in the upper steering column that could be causing this. Steering boxes are expensive!