Interesting. Does it sound like it's TRYING to read the disc? I've had drives where the laser is out of calibration and it kind of chugs along trying to read anyways. Also I'm fairly certain there's two actual laser diodes, one for Blu-ray and one for CD/DVD... perhaps that assembly is stuck or broken and no longer moving (take a look at a notebook tray drive for an idea how they work).

I can't see them replacing individual parts in the drive, they're just going to swap out the bad drive for a working one. Of course it's not an off-the-shelf drive, but perhaps you can find a PS3 with other problems and take the drive from it.