MakerBot Industries

Same way you load a MK7, open the control panel, preheat the extruder to 210 or whatever temp you use, then click the forward box to turn the extruder motor on and feed in the filament. It's not that hard.

To remove, just ensure head is at least 210, then click reverse.

I just finished building the mk7 and had the same problem. I removed one of the metal washers behind the delrin plunger, and it now works. I read elsewhere on this forum that this might be necessary and also that the washer might need to be put back later when the plunger wears a little.
Seems there ought to be a spring in the design to account for wear.