@juanmirand56436 follow this guide [guide|396] The last step shows you where the click wheel lives. It's a PITA since mine were always glued. I use a hair dryer to apply some heat from the panel side and then use a pry tool and shimmy it out. It'll take patience because of the way it sticks to the panel, it's a bear to remove. [https://www.youtube.com/watch?v=A67BEYw5_U4|They make] it look so easy at 4:50 :-)
Make sure you get the right replacement. The 4th gen and the Photo do have differences in the case.