What the heck is a detent?

The wife drives a 2003 Saturn Ion.  Thankfully, they went out of business.  She was unable to use the heat/cool on any setting but 4...and it acted like it was barely on setting 1.
The blower just wasn't functioning as it should.  After looking online, most of the Saturn community recommended buying a new Blower Motor Resistor.  I spent $50, and that didn't fix anything.
They acted like they knew what they were talking about, yet they were obviously making things up. (Source).

Finally, I stumbled upon a long post by "Willie The Wizard" in which he describes how to fix the problem.  He mentions a host of items including a plastic detent, a steel BB, and a double key. (Source).

What the heck is a detent?  I took a poly-sci class in college where I learned of "détente," which has nothing to do with a car part.  Why couldn't "Willie The Wizard" just describe these parts as
a normal person would?  Willie also fails to mention you must first take off the dash in order to access the HVAC Control.  A note to Willie:  A few photos would have been helpful.

The wife and I spent about six hours in total trying to fix the HVAC switch.  At first, we had to translate Willie's language into common terms.  Then we had to fill in the gaps.
We essentially had to realign a key that completed a circuit.  It all goes back to matching squares, circles, and triangles when you were a child...except Saturn makes everything more complicated than it needs to be.
The fan now works as it should.  I learned a few things along the way.  1) Always look for multiple theories.  2) Two heads are better than one.  3) Never trust a wizard.