The volume slider came out when I turned the assembly upside down to retrieve a dropped screw. You need to pay attention when putting it back in to make sure you line up the groove on the slider with the tiny little square bump that fits into the groove and allows you to actually control the volume. It’s easy to get it aligned if you know that’s what you trying to do, but at first I didn’t even realize what it was.

Anyway—it worked, thank you!

@Spider Gin The joystick and the tiny little control board (the pcb between the red circles in the picture of step 9) are purchased together (or at least that’s how I got mine). The only thing you need to disconnect on the analog stick assembly is the connector shown at the end of the thumb in the picture on step 8. If you are trying to disconnect the stick itself from the control board you are not looking at the right instructions for that.