I have an E3D-V6 hotend with a Bulldog XL extruder. And I have issues with it unfortunately. The first layer or so it prints fine, looks good. Then, it starts extruding less and less filament, going from lines, to droplets until nothing comes out anymore. I've mounted the 0.8 nozzle, checked the extruder, the heatbreak, cooling fan etc are all set. Temps are not dropping, but still nothing is printable. Any clue?