Denis,
11 seconds is a heck of a time for a sample!
Since I don't own a 9000 pro, can you tell me if the screen shows you the wave in all its lenght? If this is the case, it should be much easier to find a good loop analyzing the waveform and choosing two points that are at the same level (I mean two "peaks" or two "depressions"); otherwise, if you have to go by ear, try to find a loop that matches the natural vibrato of the sound. Start with a long loop and press the "find" button (all samplers have a button to automatically find a good loop) until you are satisfied with the result.
Let me know and maybe I can help more.
Andrea