Surefire sorry to here about this, I wonder if a piece of the windshield plastic went into the fan unit, but I would wait to see what Mike Reagan says before you take off the shell. I'm quite sure Lionel will take care of this quick.
Alex
The cab is actually its own contained unit, so all the pieces are within that. Going to email Lionel tomorrow and see about fixes or an RA#. Potentially taking off the shell does not bother me, and I would do so to replace the windshields to avoid shipping, but the fan noise is something I'm not so sure about.
Surefire here's the view of the fan smoke unit
If you want to look in the fan unit just unscrew number 9 and you will see if there's anything in there, but again it's up to you Lionel customer service is top top notch.
it will all workout
Alex