Is this for the mic at the bottom of the phone near the microUSB port? I'm having issues with the mic at the top near the audio jack.
Yep, I did notice you initially mentioned the mic at the to of the phone, which is why I posted what I did.
I personally don't have a need to open my phone up to see for myself at this time, but if I did I'd chronicle the process for you and share some pics.... but again, in the links I shared, pics and vid are relatively easy to follow and access those particular parts for you to see what you actually need.
That said, the assembly for the link I shared looks like it includes the ribbon for the top mic as well as the bottom mic.
Also, from the links that I shared, the teardown only shows the mic location at the bottom, which would be on the assembly. The other mic isn't necessarily shown. So, I think you'll need to do some homework and see how the tear down is. It looks relatively easy to get to, so you can see where the mic is/how it sets for the top...or if it is like the mic at the bottom.
These are what would appear to be the bottom mic
http://www.ebay.com/itm/2-x-Replacement-Internal-MIC-Microphone-for-Samsung-Galaxy-S2-S3-S4-I9300-/261421772171?pt=US_Cell_Phone_Replacement_Parts_Tools&hash=item3cddf3ad8b
So, it isn't necessarily clear if the top mic is the same or not - that's where the links are for, so you can take a look at what you'll need. Crack that puppy open and take a look.
The other thing I was thinking is that it is so close to the headphone jack, it might be a part of that assembly, which is also viewable in the teardown pics.
http://www.ebay.com/itm/OEM-SAMSUNG-GALAXY-S4-SPRINT-SPH-L720-REPLACEMENT-AUDIO-JACK-HEADPHONE-PLUG-/141236749614?pt=US_Cell_Phone_Replacement_Parts_Tools&hash=item20e25dc52e
It's hard to tell what it is exactly without seeing it upfront, so I'm just trying to help point you in the right direction...but I suspect you'll have a better idea if you can take a look on the inside. And judging from the previous links I shared, it doesn't appear that difficult to access where the top mic would rest to see what you need.
EDIT: one other thing, have you simply tried pushing the tip of a push pin or needle to possible clear any debris out of the hole for the mic? is the mic just not working at all? How do you know it's the top mic?