CD changers are very weak in terms of reliablity and the main reason is due to the large amount of moving internal components. The most common issue with CD Changers is a disc getting stuck inside the main unit. This means you won’t be able to eject the cd cartridge. It is very important that you do not try and attempt to use a screw driver to try and slide the cd back. I can tell you it will break an internal part. CD changers can jam from 3 things first being a cd was being selected while driving ( changing discs ) and you hit a bump, this causes the motor to jam up inside and when we professionally strip these down we have a 90% success rate in removing the CD and getting the CD changer working like new again.
The other reasons can be due to the lack of grease on the internal motor inside meaning the cogs, and sliders inside are running dry and this will cause the motor to trip / you thinking its jammed but all it requires is re greasing and it will work fine again. Or the last major problem is when the system breaks down internally and the unit will require a complete CD bed / mech with a new laser. This is very expensive and some times not worth while.
We have repaired countless amounts of CD Changers in the Lincolnshire area.