The car in question is a 2003 Infiniti M45.
At about the same time I realized I needed to replace my engine, my steering rack decided it had served its purpose to its original master and gave up the ghost. It's cool I guess; when it rains it pours.
Let's focus on the steering rack.
So after I replace the engine and ensure all is well, I buy a rebuilt steering rack from an ebay seller. My OEM one was pretty corroded at the outer tie rods and those were not going anywhere so I decided to just buy new ones and guesstimate the alignment for a short period.
Everything was tight, but I didn't want to chew up the tires I had bought less than 1,000 miles before I caught the coolant breach into the head. So I sent it on to an Infiniti dealer over 1 hour away to align it.
They delivered it back to me and mentioned that the steering was sloppy and couldn't figure out why, but might have had something to do with my new rack.
I'll put a bookmark here. We'll get back to this.
With the help of my phone recording, I proceeded to shake things up but could't figure out the problem. "It has to be something in this rack!" I told myself.
They warned us about this phenomenon back when I took training in conducting a root cause analysis - don't go into a problem assuming you already know the solution.
It also reminds me of motorcyle school - your bike will always end up wherever your head is facing.
If the seed is already planted in my head that it is the rack, then it's likely that I'll keep looking for ways to justify that.
Anyway, I call the vendor and tell them their rack must be faulty because everything was tight when I had my old rack, but something is loose now; which is true.
Their policy is to never give refunds, just keep sending warranty parts and the supervisor my case got escalated to insists that it must be something on my end. He says it might be my solenoid because I didn't replace that as they usually recommend. I refrain from telling him how dumb of an idea I thought that was. I mean, he could be right on the first point, but definitely wrong on the second.
So I put another deposit and receive another rack, To their credit, they pay for shipping and send a prepaid label to send it back.
You guessed it, the damn steering wheel keeps dancing and clunking and feels loose at center.
That's rack #2, from them that is.
Wash, rinse, repeat. I call again and get another rack. And you bet the steering shimmy wouldn't go away.
This is rack #3.
This time I'm frustrated with how the process has gone. I start from the top down again, I go back to the basics of problem solving - mentally lay out what I'm looking at and what it is supposed to do. What interacts with each other, and what would a failure of each component result in?
This leads me to the U-joint at the bottom of the steering column. I hold the wheel stationary and shake this joint. I don't want to believe my eyes or ears, so I reverse it - hold the joint steady and shake the wheel. I think we have the culprit.
Turns out it's a damn loose nut all this time
Back to that bookmark. I really don't want to believe that I paid for a rookie to mess around with unrelated components. Maybe I should always double-check others' work, or maybe I inadvertently did it myself. My human memory cannot for the life of me figure out why I would be down there, as there was nothing I needed to do there in my replacement. Oh well, I guess we'll never find out whodunnit
These are the losses - a front end alignment I could have avoided, a lot of time replacing 2 unnecessary racks and eyeball-aligning them, and maybe one or 2 bottles of transmission fluid.
On the positive side, I inadvertently flushed and reflushed my power steering system.
I also found a strategy in calling 1-800 numbers. Don't select the "I have a complaint" option. If you have an issue, select the "I'd like to make a purchase" option - you always get to speak to a human with little to no wait time.
Then you can try to weasel your complaint in. Doesn't hurt to try. 
