Each time I try to print the machine stops extruding. I've cleaned the whole nozzle assembly half a dozen times, slowed the print speed, leveled the print bed several times, and it still doesn't help. The cause is a piece of filament getting jammed in the feeding mechanism for the extruder. I've included a link to a picture of the jam that continually causes the problem. Any help is appreciated.

https://drive.google.com/open?id=0B0ucj6KHQJJXLTdQNGFjZ1lHVlk