[Al Skierkiewicz]

The kind of problem you describe is usually a foreign object in the drive. Depending on the object, it may already be too late to repair. Remove the power and shake the box to listen for loose objects. If you hear something, you may be able to get it to fall out with the door open. If you find that there is nothing loose, first check the bottom of the disk for scratches. If it is scratched there may be something wrong with the lift mechanism. (The part that sets the height between the read head and the disc.) If there is no scratches and no loose parts, the optical lens may be dirty. A cleaning disk from Best But or Radio Shack should clear that problem.