I had the exact same problem. I fixed my issue by disassembling the unit and cleaning/lubricating the laser assembly. In some cases there are some pots on the board that might also need adjustment.
Another thing to consider is that the Duo's are very sensitive to vibration, well mine is anyhow. Things like the rumble from speakers can upset the CD mechanism and make it skip audio tracks so make sure your console is situated in a place where it isn't being affected by vibration.