Speakers

so it's at the bottom of the speaker? Can you hear it move when you turn the speaker?

Time for a little surgery and or replacing a wrench. A great time for the speaker company to up sell ya on a better set of speakers of course, expect that Lol.

Cheers 

"Is the Allen wrench standard, or metric?"

metric is kind of the standard on this planet 😉

Try working on an American car! mismatch of metric and imperial. 

Metric is standard except in the USA.  You need both SAE and Metric in your toolbox here.