The brass needs to be polished for every show or parade.  There's quite a bit of it on this model year. More pictures of the interior brass coming soon. Often, we see pictures of others from the same model year, with varying brass parts polished. Note that the horn, and the kerosene tanks have been spotted in shiny brass in some photos, and black in others.  As near as we can tell, both are 'original'. This leaves us, apparently, free to choose what we want to have polished or not.