CX300 R2 speakerphone microphone issue

Occasional Visitor

CX300 R2 speakerphone microphone issue

I purchased a supposedly new, although manufactured 6 years ago, CX300R2 on eBay. The speakerphone microphone doesn't work. I do see in a box, something that looks like it may be the internal microphone. Is there some sort of repair manual that I can look at to see how easy it is to replace? As well, just to make sure this is the right part. I have attached a picture.

Other than a hardware issue, would there be any way that the speakerphone microphone doesn't work, but the handset microphone does work.