I'm only telling you what I think you already know - but it sounds like something inside the casing has sheared, fallen out, come undone or broken up. You've implied the motor is turning but the door isn't moving - ie the connection between motor and mechanism has failed. You're going to have to take the casing off and see what you find inside. Good luck
Richard
December 2008
Automatic Answer
We may have found other answers which could help you.