Hi,
It seems like the headphones 3.5mm audio socket is either loose from the circuit board or faulty.
Here’s an image taken from a teardown [https://www.youtube.com/watch?v=t0VxHZIACYM|video] for the headphones that shows the socket.
[image|2396275]
(click on image to enlarge for better viewing)
If it is just loose then all that may be required is that it be resoldered to the board.
If it is faulty it will have to be replaced. The hard part about doing this may be to find a compatible socket. Maybe search for [https://core-electronics.com.au/trrs-3-5mm-jack-breakout.html|TRRS 3.5mm jack breakout] (supplier example only).
I’m not sure if the example is the correct size or whether the connection pins are in the correct place so that it will mount on the circuit board in the correct place or not. It should be compatible as it has 4 poles allowing for the speakers (L + R), the microphone and a return earth connection through the cable.
Hopefully this is of some help.