If you have ever owned a Play Station 2 (thick version) you may have had deal with the "Disk Read Error" problem. At first it is not so bad, just one or two of the games don't work, but after a while almost none of the games work. You can pay money to send it in to Sony HQ and have them fix it or you can just do what they do by yourself for free.
Step 1: Materals
"Disk Read Error'" PS2
Big Phillips head Screw Driver
Small Phillips head Screw Driver
Flat Headed Screw Driver
Pen or Sharpie
Step 2: Unscrew the Bottom
Turn the PS2 upside down and use the flat headed screw driver to remove the tabs, there are 10 (only six are shown), and unscrew the screws, there are 10 (only six are shown). Flip it back over and get ready to take the top off.
Step 3: Unscrew Disk Cover
Lift up the lid and unscrew the six screws holding the disk cover on. Make sure that your PS2 is unplugged to avoid risk of shock.
Step 4: Adjusting the Optical Lens
Remove the disk cover and plug in the PS2. Press the open button and then unplug it. Find the little white gear and put a mark on it where it touches the smaller gold gear (so you can move it back if needed in the future). Turn the white gear about half a centimeter and put the disk cover back on.
Step 5: Test
Put the disk cover back on, put a game in and see if it works. If it doesn't work, open it back up and move the gear a little more. Test both gold/silver games and blue games. If Your PS2 still doesnt work you should try cleaning the lens with a cotton swab.