Save a CD from drowning

Looking for help from the audio guys here. Since buying the Caddy 4 years ago, one thing I have not been able to fix is the CD player. Got the cassette working by replacing a belt but after 4 CD units, its still coming up "ERR" when you insert a disc.

The radio and now the cassette work fine and the stock unit is fine for my uses. Mostly talk radio or audio books. Problem is that most audio books are now on CD. Have no need for newer ear drum thumping stereo (these old ears have enough issues) and besides replacing the Caddy radio with an aftermarket unit would require me to rip out the interior again to install it (seperate head unit with guts in the trunk).

Is there something else that could be causing this? Surely 4 units could not all be bad, or could they?

Any help would be appreciated. Fred was nice enough to send me up the last one from Florida and I just installed it today. Still got ERR. About ready to pitch this thing into the Rideau river.

Bill