See what Rotel has to say. In the meantime, if you have a CD lens cleaner (a disk with a little brush or pad on it that you put some alcohol on to clean it), it is worth a try. You can get them on eBay for under $10. Also try using the CD player without the shock absorbers under the feet. Does it still skip when turning the volume up?
What seems to be happening, is that once you reach a certain volume level, the vibration level coming through the player is enough to make it skip. That raises another question. Where does the CD player sit? Is it in a stereo rack? In a book shelf? Is the speaker on the same book shelf? You see where I'm going with this... How are the vibrations from the speakers getting to the CD player.
Good luck and let us know how it goes.
- Jeff