Ps2 disk drive

[supercool9]

I have gotten alot of help on all my other questions, so I was wondering if you guys could help me out with a disk drive. I have a friends ps2, and he somehow messed up the drive so it wont open right. When you pull it out, you can hit eject and it closes, but if you hit it again to open it, the thing makes a grinding noise and refuses to come open. I opened up the system, and the white peice that makes the laser come up isnt sliding over like its supposed to. Any idea's on how to fix it? or is the thing messed up forever?