Uncooperative factory radio unit

Hello...I have a 2001 Park Ave have been using a XM aftermarket and using the cassete adaptor. Suddenly the unit kicks the tape out then will not even keep the tape in. E14 comes up on the led. The research i have done says e14 is tape wrapped. No such problem with that. Any suggestions? Also if I do need to remove the unit how difficult is that to do. And is there somewhere to send for repair and is it worth doing or just try and find a new unit
Thanks!

Have you tried a standard cassette? if good it could possibly be your adapter.