The play function works fine. Without a tape in, the right reel spins when I hit fast forward and the left reel spins when I hit rewind. But then I put a tape in and when I hit either of those buttons it just makes a whining sound and the tape doesn't move. Sometimes it moves a little bit, though, as if it were trying to spin but something was resisting it or holding it back somehow. Any ideas of what this could be? Thanks.