Good thought... But the audio amps are usually heat sinled to a large piece of aluminum that is attached to the cover of the unit for heat dissipation. Another possibility is determined by how much the unit has been used, the motor that spins the cd id directly attached to the platter on which the cd rests. If the brishes are bad or there is any binding at all could cause the motor to run hot and dissipate heat to everything touching it.
Good way to test is leave a cd in the unit but do not play it. Play the radio instead. If the cd comes out hot...amps, but if it comes out cool then the cd motor. Now use the cd and check it again, if it comes out hot...then I would think the motor may be going. At any rate you should remove the unit and do a through cleaning inside of it. If you have a wiring schematic hook 12 volts to the unit on a bench with the case open and feel for where the heat is coming. If you would like, send it to me and I will find out what is doing this and repair it for you. You pay shipping both ways. No labor charges for CAC members. Parts are also extra....