Edit* fixed extruder stepper motor overheating. One last problem I am still very stumped about. Once my print reaches the infill part the extruder stops extruding properly and when I check on the print the extruder is moving pushing zero filament.
I figured it out. Stepper motor current was too high. Filament was getting snagged on XYZ's terrible filament cartridge (I need a filament wheel & need to use up the XYZ filament to get better quality filament). Gears in extruder were too tight. Idler wheel was loose. Cooling airflow of MK9 had to be tweaked to hit extruder and not the heated bed.
The MK9 is working great now.
And how do you reduce the stepper motor current?
From his other posts I suspect Barry has possibly switched to RAMPS.