Additional application of heat and thinking solved it.
I was heating the box housing, not the lock nut itself. Helps to expand the nut if you're trying to loosen it
. Also switched from hitting it with a rubber-handled pry bar to an all-metal bolt, which helps get a nice shock load in there.
Anyway, got it off and the rest of the rebuild went pretty smoothly. Getting the ball bearing cups out of blind holes required a little bit of creativity; namely heat, PB blaster and assorted pull/pry tools.
The ball nut has very minimal play on the steering shaft and no tightness/binding, so I just left it intact.
I don't have an inch-pound torque wrench that goes down to single-digits, so I pretty much snugged things up and guestimated torque while twisting the shaft for the ball nut adjustment, then doubled that guestimate when doing the sector shaft. Depending on time, I might go see if I can pick up a dainty torque wrench.
Pulling that box out of the car reminded me a lot learning (and observing
) how a baby makes it out the birth canal (twist, push, rotate, push this thing out of the way, push harder and swear). Based on that...not looking forward to putting it back in.