Thank you everyone for your advice. I want to give the final resolution (I hate when you search a thread and the original poster doesn't take the time to say what ultimately happened)

The dealer refused to warranty the slave until I replaced the power steering pressure tank. I did. And, as predicted by everyone here, the fix did not work.

Now out $800 and time, I insisted they replace the slave. It took a lot of haggling and aggravation, but they eventually replaced the slave and accumulator under warranty.

And, again, as predicted by 6 Speed Online, that was the fix.

Thank you everyone for the help!

Good to know but it goes without saying that they should have made it right the first time.

Good news!!!! Another happy TT owner!!!

True.

Their excuse was "we normally replace all of those parts together because they normally fail together." Curiously, their original diagnostics form failed to mention that...

However, it is still a 13 year old car, and if we want everything to be under warranty, we can pay $180,000 for a new one. I'll take my $40k version and spend some on maintenance.

And I do have a perfectly good used pressure tank if anyone is hunting!