Like many people, I have burnt the pins in the micro-controller connected to the E0 motor - the E0 motor is not working anymore and I need to print tomorrow! I need to control the extruder motor with the working E1 pins. How do I change this in firmware?
I tried to change to the pins in `pins_RAMPS.h" but it was a complete fail, the motors that i tried to change didn't move.
I have a Arduino Mega + Ramps 1.3 in "Extruder Fan Bed" configuration, I use Repetier-Host as host and Marlin as firmware.
As a quick and dirty solution you may try to enable two extruders in configuration file, re-upload firmware, and then edit your GCODE file to replace all E0 references with E1.