Trying to show one of the several issues I've had with the QU-BD extruder. This video shows a problem others have had where the filament extrudes easily for a short time but becomes much harder to push through until it stops. This test was with makerbot PLA at 210°C. The same thing also happens at lower and higher temperatures.
![](https://s2.save4k.ru/pic/u8uCGKmev9o/maxresdefault.jpg)