Is there any way to “tweak” the PS2 laser bias adjustment?
You’ll probably have to replace the laser. I’ve seen the instructions for adjusting the XBOX DVD drive’s laser on the web, but not for the Sony. Do some searching and see if there are replacement DVD drives for the Sony. Buy a new drive and put it in yourself if you can’t find the pot on the original drive to adjust it. It might be that Sony uses such crappy drives that the laser isn’t adjustable on them. I don’t know for sure… google will surely help.