Reprap Pro Mendel extruder problem

Hey guys.

I have bought and build a Reprap pro mendel, from reprappro.com.

I have printed different print with different result and has tweaked and calibrated here and there.

I am now trying to print a bigger print and the last two try the extruder has starting clicking and just moving back and forth. It happen both time, after approx 5 - 6 hours of print time .

I have tried to clean out the nozzle and PTFE tube without luck.
I have measured the voltage at the pot-meter at the stepper controller and have raised it from 0.6 to 0.7 V. Without luck.

I have put a fan to cool down the step controller and have put a heatsink on the extruder motor. Without luck.

Today I tried to start the printer again, but during the first layer the stepper start clicking again.
See video: [youtu.be]

Anybody got any idea, what to do?

Additional info from firmware.
echo:Marlin 1.0.1 RRP
echo: Last Updated: 2013-03-26-RJ | Author: RepRapPro
echo: Free Memory: 11517 PlannerBufferBytes: 1232
echo:Using Default settings:
echoteps per unit:
echo: M92 X92.635 Y92.635 Z4000.000 E660.000
echo:Maximum feedrates (mm/s):
echo: M203 X300.000 Y300.000 Z3.000 E45.000
echo:Maximum Acceleration (mm/s2):
echo: M201 X800 Y800 Z30 E800
echo:Acceleration: S=acceleration, T=retract acceleration
echo: M204 S1000.000 T1000.000
echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum xY jerk (mm/s), Z=maximum Z jerk (mm/s), K=advance_k
echo: M205 S0.000 T0.000 B20000 X15.000 Z0.400 E15.000
echo: M206 X0.000 Y0.000 Z0.000
echo: M208 X210.000 Y210.000 Z140.000
echoID settings:
echo: M301 P12.000 I2.200 D80.000 W125
echo:Thermistor settings: M304 Hh Bb Rr Tt, H0=Bed, H1..n=nozzle, b=thermistor beta value, r=series resistor, t=thermistor resistance as 25C
echo: M304 H0
B3480 R4700 T10000 M304 H1
B3960 R4700 T100000
FPU Enabled no
transform correction not enabledechoD card ok

Here is a download link for the last version of the G-Code i was trying to print:
[dl.dropboxusercontent.com]

Thanks in advance.

So I tried another again and start monitoring every little thing. I found out, that the nozzle temp, will suddenly turn off. Dont know why, but that is a problem. Now I will try to see if I can solve that.