screw off the screws and sheetmetals and baffles on the both sides of the CD drive

install the screws and sheetmetals and baffles onto the hard disk tray

use screwdriver or electirc screwdriver to release the wire in the wall from the switch

use screwdriver or electirc screwdriver to screw the wire in the wall into the screw of the new switch

let the flat side of the new needle towards the jack and insert the new needle

add some cleaner to clean and wet the lenses and take out the lenses