Well it turns out that if you have the old style print head without quick release levers, your extruders will fill up with ABS dust over a year of printing. I didn't know to clean the extruder so it finally hopelessly clogged just before Christmas. Mark and the team rushed me a new mk9 print head and I installed it after removing the wiring loom tube and figuring out what the wires were: There are two stepper motors "A" and "B". the Black terminal blocks for the thermocouple, heater and the fan are paired with the "B" stepper motor on the right side. The A stepper motor on the left are paired with the wires terminated with Green Terminal blocks.
On my model, the thermocouple leads were blue, the heater leads were both red and the fan leads were red and black. Care must be taken to make sure that the left thermocouple is connected to the left thermocouple terminal block on the motherboard and the left heater is connected to the left heater terminal block on the motherboard, or the board may not sense the block has reached temperature and continue heating until the head is destroyed.
The fans activate when they reach the user definable fan temperature (in my case 70C). I successfully tested both extruders and fans, and did a test extrusion with both and have been printing happily ever since.
Thanks Mark and 3dprintersuperstore!
