That's great investigative work, Chris - my hat's off to you.
I used that Tone library following the steps of the Instructables for the Simon Says portion of the code. Since I got that to run, I assumed that I could add servo motion to the program.
Now that I have your explanation, I'll see if I can get it to work using the built-in tone function. I already started on that, saving a stripped-down version of the program without servo movement, and reading up on the tone function, which seems to take three arguments. I'll see if I can match those to the ones in the .h file of the old Tone library.
That's a fundamental behavior I didn't know existed, and for a beginner, it's daunting. It means that to debug a program, I have to understand not only my own code, but all the code from any libraries used, as well as how different libraries interact. Yow.
I may need to swap back since my project is due tomorrow night (I was working on the Knock Lock project for Tutorial 12 but found I needed a different speaker, which I now have). But first, I'll keep going with this and see if I can make enough progress today in re-writing the speaker code. Thanks again.