Steering rack ajustment

When there is that much play, something has come apart inside. Those adjustments don't change by themselves. Racks are not repairable by us since we can't buy parts for them, but I had my students disassemble some each year to see what was in there and how they worked. If you're talking about the cap under the steering shaft / input spool valve, there is a spring-loaded insert that puts pressure on the valve to hold it in position. That isn't really an adjustment. I had a couple we autopsied when they had the play you described and it turned out to be a problem with the spool valve itself. The symptom was no power assist in only one direction until you tugged really hard on the steering wheel, then all of a sudden it would break free and turn easily, but there was a knocking sound that could also be felt in the wheel. That would intermittently affect turning the other way too, and sometimes it worked perfectly fine for entire minutes at a time.

Can you, ... Uhm, ... Point to or name the part you were thinking of adjusting? Where are you seeing that half inch of play?

That shouldn't leak there just from loosening the lock nut. There isn't much pressure there depending on where the end seal sits. With that much play though, the pinion gear should be skipping over the teeth on the rack and there should be horrendous fluid leakage from the boots.

What I would suggest is removing the lock nut, then remove the adjuster completely, (mark it and count the number of turns), then check to see if that spring is broken. From my limited experience watching students take these apart, I'm more inclined to think you're going to find the rack pad is broken. It is usually made from nylon. Its purpose is not to set the amount of play, because there should be no play, it is to set how hard the rack is to move back and forth.

If you find the spring or pad broken, I'd head to the nearest pick-your-own-parts salvage yard to find those parts in a similar rack. There's only a few manufacturers so you might find the same parts in a different brand of car.