The internal speaker is wired to the circuit board but not welded. If you have a replacement and the soldering skills to install it, this guide will help you identify and remove the internal speaker.
Remove the two screws on the bottom of the device with a Phillips head screwdriver.
Use a spudger to remove the plastic plate from the bottom of the player.
Use the spudger to push the USB port on the bottom of the device inward.
Hold the device firmly between two fingers. Be sure you aren't holding down the top of the device; the circuit board will slide out of the shell through that end.
The plastic LCD cover and the key pad will now be free; they were held in place by the tension between the case and the internal circuit board.
Identify and pull the speaker away from the device.
Use a wire cutter to sever the red and black cables connecting the speaker to the circuit board.