possible the track is misaligned, When the CD tray is fully extended give it a pull, with just a little force both to the left and to the right to see which side had misaligned on the tracks, if it is misaligned it will click as the tray jumps up one on the tracking. If you don't get any clicks then completely remove the tray from the tracking and then reinsert and push the tray to the closed position.
Mind you, this is if it will come out. Also, this could break it it too much force is applied.