This will show you how to :

Replacement PS2 Parts
Playstation 2 Maintenance (With VIDEO)
Disassembling you’re PS2 (With VIDEO)
Laser Cleaning Procedures (With VIDEO)
Adjusting the Laser Voltage (With VIDEO)
Adjusting the Laser Height (With VIDEO)
Replacing your PS2’s Laser (With VIDEO)
CD Tray Alignment (With VIDEO)
Testing Fuses (With VIDEO)
Desoldering & Soldering Fuses (With VIDEO)
Common Playstation Problems and Fixes/FAQ
Power Supply Troubleshooting and Diagram
Precision Laser Adjusting with O’Scope
Disk Read Error
Find Your PS2 Version
More on Disk Read Error
Buying PS2’s to Repair
Replacement PS2 Parts

This tutorial is very detailed and very easy to use for ANY one
http://rapidshare.com/files/8494511/ps2_Repair_Guide.exe