I have solved the "blue prints as purple" problem.
I set the "Rendering Intent" on the plotter to: "Perceptual" (This is best for photographers)
I then changed the software driver (on the PC) "Color Management" from "Default" to "Printer Color Management". I also unchecked "Automatic Pantone Calibration". By selectin "Printer Color Management", the settings are "Standard Emultation" which uses "SWOP" for CMYK and "sRGB" for RGB Monitor.
It sounds complicated, but it was actually just 3 settings that I changed.