My left joystick is making a clicking noise

Recently i had let my nephew use my device and once i got it back i noticed that the left joystick was clicking when i moved it every few seconds, as if there were an L3 button on the divice. I need to know how I can open my vita safely so i can be able to readjust the joystick. The joystick works fine. Buts its the clicking makes me think that it may be out of line causing a gap making the clicking.