Refurbed boxes seem to have a bad reputation, and new ones a price tag that will buy you a whole Disco parts vehicle. Given that I've got three steering boxes lying around now, two that wobble and one that leaks, I thought I'd pull the leaky one apart. Sector shaft had pitting round the lower seal, unsurprisingly. There's a roller integrated into the shaft whose non-repairable bearing had brinelled quite badly, so I pulled a sector shaft from one of the other boxes that until recently was on the Disco.
Incidentally, when the LR Workshop Manual tells you how to dismantle a box, it really goes round the houses. If you just want the sector shaft out of there, take the Pitman arm off the bottom, undo the four bolts from the top, and the shaft pulls straight out. Takes five minutes. Doing it by the book takes an hour or so and leaves you with a shedload to reassemble...
Anyway, the second steering box was in a bad way - fluid burnt brown and full of particles, lower bearings both collapsed, shaft badly scored:
Howeve, the roller and its bearing are in good order. I've got in touch with a local hard chrome specialist to see if they can restore the bottom end of the shaft. Not sure it'll fit on their centreless grinder but if worst comes to worst I think I can prevail upon a friend to prep and grind it and just use these guys for the actual plating. Will report back once I know a) whether it's actually possible and b) whether it's affordable. I'd rather this than a recon box as then I know that the money has been spent on the bits that matter, i.e. the shaft isn't going to grind the seals to dust over the next three months or so.
Nice to understand the difference between how the two boxes feel on the road, at least - the leaky one had intact lower bearings and the difference in handling was night and day. If I can get one box sorted for the daily driver, I'll follow up with another for the project truck.