Please help, blackscreens

[williesbest2]

This doesn't happen on every game but only a few. The first game Star Ocean: Till the end of Time won't read, it just gives me a black screen when I try to play disk 2 (I have completed disk 1). Now MLB 2K5 is also giving me a black screen. I need help. I'm desperate. Does anyone know how I can fix this.

I have tried:
Cleaning laser
Compressed air
Disk cleaners (cd kind)
Adjusted laser according to directions below

This PS2 is no longer under warranty. Is it possible for me to replace the laser or the optical drive (I've done this for my Xbox already). Just someone please help me. Thanks. Also this is not a modded PS2.