Extruder not holding temperature

Hello

I just received my Robo3D and I'm trying to print a calibration cube (15mm cube from this thread: http://forums.robo3dprinter.com/index.php?threads/just-got-your-printer-things-to-keep-in-mind.1161/). The problem I'm having is that during the print the extruder temperature drops and I start to get messages "echo: cold extrusion prevented". The first few layers look OK, but soon after it can't print any more. I'm using the PLA that came with the Robo3D.

I've noticed that when I home the extruder assembly on the X axis it looks like it switches off the extruder also, which implies that a wire is loose or being pulled. What do I need to look at? I've started to trace the wiring but any pointers would be helpful.

Thanks

This is the temperature plot during the print. I started at minute 30 and aborted the print at minute 34. According to the log it printed two layers then the "cold extrusion prevented" messages started.


Here's the temperature plot after the print. I X-homed the extruder at minute 48: