I found an old Gamecube at a second-hand store going really cheap. The catch was, the disc would spin up, and then stop again (with no disc message/indication).
If the drive detects no disc, it won't spin the motor. So if your laser is dying, and it cant see anything, it wont spin the disc.
So it is possible that the laser is dying/almost dead, but there ARE guides out there that may help with this; just google "gamecube laser calibration" and hit the first link.