Hey everyone, new member here.
I recently got a 1991 RX-7 vert from a friend and while I was inspecting the car I noticed that the volume rockers for the Headrest Speakers are faulty. Is there any way to check if the wiring is an issue or if the part needs to be replaced? Attached is some pictures of the panel and the wiring behind it.

 

All 88-91 convertibles use the same switch box. I forget which manual has the internal diagram. Situations like this are why it is good practice to have both the 86-88 and 89-91 manuals.

When you press either rocker, its output wire is connected to ground. Since it's a SPDT momentary switch, it has two outputs (up and down). I highly doubt the switch box is faulty, speakers are a more likely candidate for failure after 25 years. The second likely failure point after the speakers would be the original stereo itself.