Unusual Legacy issues with R&N steamer

To your second point first, this is usually happens when the speed control is nudged.  If you have shut the engine down, it will creep without making any noise.  The easy fix is to change the CAB2 to an unused engine ID.

Back to your first question, have you noticed whether the cab light is blinking?  That will tell you something about what is happening.  It sounds like it might be a motor problem, if so you should see one blink every second or two.  Since this locomotive is still under warranty, I would not fool around with it.  Contact Lionel and get an RA.  Be sure to explain the problem as clearly as you can and include that explanation with the locomotive so the tech can understand what you are seeing.

Let us know how you make out.

Thanks Dan for your help.  I made the mistake of including this engine in lashup “1” and this probably led me to brush 1 when addressing other lashups.  
i hope the second issue might have corrected itself.  But if it happens again i will be more alert to events leading up to the engine refusing to move when everything else seems ok.  Thanks again.  Phil