So I bought the Ultimaker 2 a few months ago and was pretty happy with it. After a few prints, the extruder clogged, but I was able to fix it using the Atomic Method. It began clogging frequently, but I was always able to fix it until last week. After trying everything short of taking apart the print head, I decided to switch from the gray PLA that came with the printer to some ABS that I had bought. Lo and behold, it worked perfectly (other than some warping issues). After a few prints, I figured I could go back to the PLA now that the nozzle was seemingly clear, but it didn't work.
Here's what happens:
When I am in the process of changing filament to PLA, I can get all the way to the step where I am waiting for the filament to begin extruding from the nozzle. When it gets to the nozzle, it starts making a loud clicking sound and won't come out. I tried using the "move filament" tool as well, moving it back and forth to no avail.
Any ideas as to what the problem may be? I can't really understand why one plastic would work (ABS) and another wouldn't (PLA)...