I am 4th owner of a 2002 M5. I've owned it for a few years and the audio is still the stock M audio with 6 disc Alpine changer. Being a bit "old school", I have tons of CDs and still listen to them at home and in most of my vehicles.
Like many on here, I have experienced periodic jamming of the disc changer. Usually, a good swat on the changer would get it working again, but it would always jam again. Even had a to stick a small screwdriver down in changer a couple times to loosen a stuck CD and tray.(I know, probably not smart). This last time, nothing was working, so.......
I pulled out the changer and disassembled it, taking off case(small Phillips head screws and some finagling). I couldn't see anything in the mechanism obviously broken or out of place. I was able to push the tray and stuck CD back into the cartridge and noted that small amounts of what looked like lithium grease were used at some friction points. There are numerous sliding friction points, pivots and gears in the mechanism,incliuding slots in the inner metal case, so I lubed them all with fresh lithium grease.
So far, so good, with no malfunctions. Maybe the various friction points get dry and stick, causing malfunctions?
Just a thought. Will let you know if it recurs.