I just installed the 2nd print head in my Vertex printer and the extruder will not feed. I swapped ext 1 and ext 2 wires to see if it was the motor and the motor is running so that rules out the motor. I swapped the 1.5 amp driver chips and that did not fix the problem. The firmware was updated to the 2 head firmware. The nozzle does heat up and the extruder says its loading but the extruder does not run. Any suggestions on what to do next?
When you updated the firmware did you use Arduino software version 1.0.6 or lower?
You can download it from here.
https://www.arduino.cc/en/Main/OldSoftwareReleases#previous
You should also post in the Vertex section this is the K8200
You will get a reply faster.
Hope this helps.