Lift the motherboard off the base and flip it over to access the headphone jack. Make sure you have the right port; check that it's shaped for headphones to be plugged in, and not the charger.

There will be a total of five connections between the headphone jack and the back of the motherboard; desolder all five. See this guide for information on how to desolder connections.

Remove the desoldered jack. It is now ready to be replaced.