The problem with the burnt discs, (if you didnt already know) is some are much thicker than normal retail music cd's. I tore my cd changer apart because when I bought it it was already jammed, there were 3 cd-r's and the rest retail cd's. the retails slid right out just fine, but the cd-r's were pinched just enough to not be able to push out...
<disclamer - I do not take any responsibility to what happens following the below>
I did have a friend get frustraited with one of his changers (different vehicle), he pulled it (power and all) and then lightly sprayed some silicone into the changer, let it dry, plugged it back in, and hit the eject button and the disc came out just fine. Then he threw in one of those laser lens cleaner disc with cleaning solution to clean the lens of any mess he made. needless to say, it actually worked and the changer was still able to read cds no problem. just remember to not stuff a cd-r that is abnormally thicker...