Problem with 12 CD changer

I have a 97 GT. It has a Delco AM/FM/Cassette Deck with Equalizer in the dash and a 12 CD changer in the trunk. The car is also equipped with steering wheel controls and the HUD which are both connected to the stereo.

The changer only reads 4 of the 12 discs and even then has trouble doing that. It is slow to read or I have to change tracks to get it to work. I am looking for any advice on what it could be and what I can do about it.