There is a problem recording or importing files using Mpeg Layer 2 at 128kbs in Mono. The actual length is shortened by several seconds, and the play back may cut off 2 or 3 seconds at the end of the cart, as if the aux mark was incorrect. Solution: change to the next higher bit rate, 160kbs, and the length will be calculated correctly. The aux marks will now also work, and the cart will play to the end.