Yep, have had a factory DCC-fitted example delivered and it does the same thing. Have run it on both my Lenz-controlled system and my Bachmann-controlled system. Same issue on both. My take is that there is a lot of 'slack' in the drivetrain. There is, in my experience, more 'play' in the drivetrain of this model than I've encountered in any other. You can actually rotate the wheels quite a way by hand. I'm guessing that, as others have speculated, that is playing havoc with the control on DC and especially BEMF on DCC. Interestingly, I have two other examples of these railcars, both of which I fitted DCC chips to myself, and they exhibit the same issues. But you can greatly improve things, at least in my experience, by turning BEMF off and increasing the values on CV3 and CV4. Well, that works for me anyway. It's not a perfect solution but was 'acceptable' to me. As for the factory fitted DCC example, that's going back.