I've had this unit since the 80ies but rarely used it. I finally get around to doing scratch tracks (one track) just recording ideas that I would later expand on in ProTools. I have less than 5 hrs recording time on this unit. I pressed play and record buttons and now the heads are locked in the up position.I had to break the cassette just to remove it. I can physically push the heads back down where they belong,but they snap back up. I am thinking this HAS to be a mechanical problem. Any ideas?