We bought a Ultimaker 2 Extended over two weeks ago and it seems like it has resulted in seemingly endless problems. We bought the machine to save time and it has done just the opposite! Before we return it and get a different machine, I wanted to post the latest in many problems. It is that the material stops feeding and "grinds" to a halt. The head seems perfectly clean and material seems to flow very well. The spool is free and the material comes off without much resistance. Looking through the blog, this seems like a problem that has been around for years and yet is still not solved by Ultimaker. FYI, we are printing organically-shaped parts (heart, lung, arteries and veins) using PLA for material and Simplify 3D (as Cura would not produce enough support material regardless of settings). Any thoughts would be greatly appreciated! Thanks.