I had a CDP 300 with the same problem. Cary was using Pioneer transports and the glue used to hold the laser cover would fail. Mine came completely off and would not read any cd's. Cary was able to re glue mine and service the player for around $150.
new laser/assembly for Cary 303/300 cdp
The laser is going south on my CDP giving me a lot of "no disc" messages. Just wondering can the laser or laser assembly be sourced a lot cheaper anywhere else but Cary?