Note the location of the internal-speaker cable connection. Note the routing of the internal-speaker cable. Disconnect the internal-speaker cable from the system board. See "Locating system board connectors and components".
Use a blunt instrument (such as, the top of a ball point pen) to disengage one of the internal-speaker-locking tabs 2 and slide that side of the speaker 1 upward enough to keep the locking tab disengaged. Then disengage the other internal-speaker-locking tab and slide the internal speaker upward until the speaker is released.
Remove the speaker and speaker cable from the computer.
Route the speaker cable and then position the new internal-speaker tabs 3 into the metal speaker slots and then push the internal speaker downward until the speaker-locking tabs snap into position.