The Xbox 360 uses a laser in its DVD drive to read game discs. This laser uses an average setting that doesn't always work, so sometimes a disc refuses to be read. Adjusting the laser will eliminate this problem, but this job is not for the casual user.
Put the clean cloth down on a work surface. Remove the power cord and audio and video cables from the Xbox 360. Put the Xbox 360 down on the clean cloth.
Put two fingers of one hand inside the door where the USB ports are. Squeeze the top of the faceplate with the other hand and pull the faceplate off. Put it aside.
Wiggle open the right side of the case. Insert the long stick through the white holes inside to release the tabs holding the grey piece of plastic inside.
Press the front button on the Xbox 360. Wiggle the left side of the case and repeat the procedure done to the left side.
Slide off the two side panels.
Use the flat-edged screwdriver to release the tabs on both sides of the case that were hidden by the side panels.
Remove the screws from the side and back of the case with the Torx screwdriver. Put the screws aside.
Pull off the front cover of the Xbox 360.
Remove the DVD drive from the Xbox 360's case using the jeweller screwdriver. Put the screws aside. Lift the DVD drive up and pull out the power plug and the data ribbon connectors.
Put the DVD drive down on the clean cloth. Take off the sticker and remove the screw with the jeweller screwdriver. Remove the screws on the side of the DVD drive with the Torx screwdriver and put the screws aside.
Turn the DVD driver over and pull off the top. Remove the screws holding the heat shield to the DVD case with the jeweller screwdriver and remove the heat shield.
Pull out the serial connector attached to the case and slide the DVD drive electronics out from the case.
Jiggle the circuit board to loosen it and then lift it up. Pull out the ribbon cables and put the circuit board aside.
Position the drive so that you can see the potentiometer (the "pot"), with one contact on the pot situated on the left and two contacts one above the other on the pot situated on the right.
Set the multimeter to the "200" setting. Place one wire from the multimeter on the pot's left contact and the other on the pot's lower right contact. Record the reading from the multimeter.
Adjust the left contact using the jeweller screwdriver and take another reading. Continue adjusting the screw until the reading reads 1100.
Reassemble the DVD drive and put it back onto the Xbox 360 case.
Reassemble the Xbox 360. Plug the power plug and the audio and video cables back into the Xbox 360. Turn the Xbox 360 on and insert a game disc and start playing.
Wear an anti-static strap to eliminate static electricity, which could destroy the exposed electronic components.
Opening up the Xbox 360 voids the warranty. Microsoft or an authorised dealer will not do any kind of repair on it afterward because of this.