I recently purchased an Ultimaker 2 and unfortunately the nozzle became blocked during an overnight print. This resulted in a build-up of residue (carbonized plastic) in the nozzle. I tried cleaning the nozzle but was unable to get it sufficiently clean.
Instead I disassembled the hot-end and replaced it with the "Olsson block kit" (replaceable nozzle kit). During assembly, I watched this video:
I noticed that the Ultimaker in the video had no bent plate protecting the back of the printer head. Mine does, and I had to bend this to fit the heater and temp sensor cables without damaging them. See image: http://i.imgur.com/O2OMSn5.jpg
Now the hot-end heats up okay, and I can feed plastic through it manually if I remove the bowden tube, but I cannot get it to print using the feeder. It seems it takes a bit too much force to get the printer to move material through the nozzle, even if I change the pressure setting on the feeder, it cannot extrude any plastic.
Does anyone have suggestions on what steps to take?