No extrusion during print

Ok, I'm still relatively new to 3D printing firmware but decided I could take on the task of building a P3Steel after a successful few months with my OneUp. Build is complete and calibrated. I went to do a test print of 20mm cube and the extruder will not extrude any plastic during printing. During pre-print it does just fine commanding an extrusion through RepetierHost. After a week of unsuccessful attempts I come to you guys for some help.

Here is some info in case it is needed:
E3D v6 hot end .4 brass nozzle
Marlin Firmware (not sure on version will check later)
Gregs Wades extruder

I'm sure that this has been covered on here some where but have yet to find it. Any guidance would be helpful!

Is the printer moving like if it was printing or just hands there doing nothing?

If it's moving but not extruding, first check your g code for stepper movements, it will say X follow by a number, Y, Z (if ABL is active) and E, E is the extruder so the number will indicate how much extrusion will take place. If everything is right in there, check temperature settings, be sure it's getting to the setup temperature, if all that's gine then check for disabled stepper, faulty connections or stepper driver cutting down because too hot.

Quote

the extruder will not extrude any plastic during printing

So, what does happen? Does the extruder motor turn? Does the extruder motor click or buzz? What do you see in the Repetier log window?

Check that the nozzle is showing the right temperature. Too low nozzle temperature will cause the software to prevent "cold extrusion".

And make sure you don't have dry run turned on - its happened before.

On first look it looked like the extruder gear was barely moving so I ramped up the e-steps. Was still having problems. Upon closer inspection in the slicer settings I realized I had the layers set to 0.02 instead of 0.2. It does not pay off to work on no sleep!! Thanks for the replies though.