You are correct John - blue is "Steam Into Cylinders" and "Steam Out Of Cylinders"
The cores are: red - exhaust, green - live steam, light blue (and underneath dark blue) - main lightener, tan - frameway, brown - cylinder bore, dark blue steam port, darker green - outer lightener. My model represents only one quadrant of the complete assembly - the left and right cylinders are identical and formed from the same molds