so you need a new DVD drive. The best way to do it imho is to swap DVD mothor boards from the old drive the the identical new drive. (If you are set up for it, flashing the old key on new is easier, but only if you have the correct tools/software. both are super easy, id give em a 1 out of a 10 scale for modding either way)
Since that error is a mechanical alignment issue/ failing Laser, the mobo from the original will more then likely be in perfect working order. So simply swap the Mobo with the correct keying into a new/working drive and whalaa your all done.
Our friends over at Llamma.com have plenty of dissassembly tuts for most of the drives.