Solved Exstruder Not working

I have swapped the extruder stepper wiring harness to x and the stepper motor and associated wiring works. I have replaced the motor driver, the Mega and the Ramps breakout board. I even reprogrammed the firmware, it still will not extrude. Any ideas?

I am a very experienced customer, so I'm not a newb, please respond as such.

 

Just a check because I have fallen into this before, you are heating up the hotend to temp prior to extruding? Is this an issue only when printing? Have you done a manual extrude?

 

When it was cold a safety built into the software prevented it from moving. When it was hot, there was a jumper missing under the Ramps driver.

Better now.

 

So a missing jumper solved it? Great news. I know some forget about the min extrude temp setting in the firmware, so i always ask first when I hear folks with extruder issues. Glad it's all cleared up. Cheers!