Does anyone know how to repair the mic?

I tried fixing mine today and it seems to have worked. But this is definitely advanced level. My current assembly state is this

I did not have a repair cable thin enough to fit through the hole, so I cannot put mine together right now. Jabra used a coax cable with wires as thin as I have never seen before. The hole in the PCB is not much bigger than 1mm in diameter and it proved difficult to find a cable thin enough.

This is the back of the PCB as found

This is what it looks like after desoldering and preliminary cleaning

What I have learned so far: the black plastic they put on the solder pads and in the feed through hole can be melted with a soldering iron and removed with a fiberglass eraser. Unfortunately, I did not have one at hand so I used a flat tip screwdriver for temporary cleaning. That's why it's not as clean as I would like it to be yet.

The mic boom arm is filled with silicone and the outer casing seems to be glued shut. I could not find a way to open it up yet so a full microphone replacement seems unfeasible.

Microphone cable replacement also seems unfeasible because the cable is also glued to the end of the actual mic in the boom arm with silicone.

I couldn't get even a beep through-measurement with my multimeter, let alone an internal resistance measurement. Probably because the cables are so thin. Plus inside the coax cable the insulation between the inner and outer cable layer is just some sort of insulating paint so it is really difficult to get a proper contact. However - after soldering in a temporary cable for testing purposes (and some fiddling with the switch in the headset that mutes the mic when the arm is flipped up) it did work in a test call. So the mic worked after temporary reassembly but I am still doubtful that I will be successful. I ordered a fiberglass eraser and a 0,04mm² cable (could not find a coax so let's hope this one works) and will try to put mine together afterwards. I am not entirely convinced that I can even manage that. If I am successful I'll try to write a manual for the repair. But I still have my doubts. Mainly because of my skill level (or lack thereof). Someone with a higher skill level and better equipment should be able to fix the headset.

I'll also try to get some damaged ones from some colleagues and then try and fix those before posting the manual to make sure that I actually fixed the problem and mine wasn't just an outlier. My mic was still working on and off before I tried fixing it.

We also use the same headset in my company (or better - used to use..we have to take the cheaper model nowadays). The headsets kept failing after a while, usually after ~2 years.

My first recommendation is to check, whether you are eligible for a warranty replacement. In my region (Germany) Jabra Headsets have a 2 year warranty and Jabra has an easy to use online warranty checker. When I RMA'd mine I did not have to hand in any proof of purchase and I did also not have to send in my faulty device. They just sent me a replacement unit free of charge.

A colleague of mine tried to repair his and was unsuccesful. He said that the microphone boom cables are routed through a hole in the PCB and are then soldered on the speaker side. He did not see any damage in the cables (then again - his mic was working every once in a while). He didn't want to take the headset apart any further so he cut the cable a little ways off the feed through hole and soldered new cables in but did not solve the issue. In fact - his mic stopped working altogether even though the measured resistance seemed to be fine. He then abandoned the repair effort.

My warranty replacement unit just died because of the microphone issue so I'm going to try and repair mine if I find the time.

That’s usually the problem wear and tear of this wire. It contains 2 wires inside, make sure to isolate them correctly after cutting them open and resoldering it.