Initially, there was no communication between the stand-alone add-on CD player and the main unit which consists of AM/FM radio, dual cassette recorder, 3-band graphic equalizer. I cleaned all the boards on the cd player and now it is able to recognize the number of tracks on the media. However, it still will not play. I think there might be a solution in the documentation, because on the back of the system is printed: "See Instruction Manual for System Control from Main Unit" Main Unit Model No. - 11-8040 A Stand Alone CD Player with comm ribbon and modular jack for input to main unit Model No. - 11-8040CD A