DVD drive won't read many disks

Hi,
I have a Compaq Evo N800c notebook computer, and they DVD drive won’t read many disks, and sometime get read errors. I tried cleaning the laser, but it did not completely solve the problem. I think my next step would probably be to try to realign the drive, but I don’t know how.

Any ideas on other things to try or on how to realign the drive?

Thanks