Hello.  I am relatively new to the hobby of model trains.  Recently I purchased the Bachmann White Christmas N scale set.  After setting it up today and running the train, I noticed that on slower speeds, the engine is extremely choppy, and sometimes unresponsive.  Is there anything I can do to fix this?  Also, the headlight on the engine does not light up, and I believe it is supposed to.  Thank you in advance for any responses.