GKaindl supplied us with this addendum to the Machines.xml file in RepG and that at least helped me get the extruder spinning for tests;
RepRap Mendel
<!-- Z uses the same pulley, but is geared down pretty hard -->
<!-- optional, defaults to first serial port found. COM1 -->
<!-- required: we need 8 bit and 38400 baud. -->
384008
<!-- optional, defaults to 1. 1 -->
<!-- optional, defaults to N. N -->
0
(Turn off steppers after a build.)
M18
Naldarn thanks for getting back to me. I kept the motherboard powered and held down the reset button until I saw white text in the bottom of the monitor, as suggested in the firmware installation folder.
I am unsure where the firmware available on RepG and the 5D firmware took a fork in the road, I am using v1.6 firmware for the motherboard, and v1.8 for the extruder, later versions of firmware on RepG didn't see the new additions for stepper driven extruders.
It seems that my earlier decision to switch might not be the fix I'm looking for, as neither firmware turns the extruder during a print, and I'm currently scouring the internet and forum landscape for missing data I need to plug in.
Lines of MCode? additions to configuration.h?