3D printer extruding too thick Last night there was an error in printing that caused the printer to stop printing, but kept the hotend on. This morning I discovered that it had fused to what it was printing after renaming on all night - it took some time to remove. 

Prints afterwards showed signs of under extrusion. Now when I tell it to extrude a millimeter, it no longer extrudes a thin strand, but instead exactly a millimeter of filament comes out the same diameter as it went in. Cleaning the hotend has done nothing, cleaning the extruder has done nothing. 

I'm left with two conclusions, either:


this is what is supposed to happen, it was broken the whole time, I had calibrated it for the broken setting and just need to recalibrate everything, or;
something, most likely the nozzle, is broken.
When you have a disaster print like this you almost always get carbon in the hot end. I have micro hand drills (0.2 mm) that I carefully use on the tip of the nozzle. There are also atomic pulls where you add plastic, heat it up till it extrudes then let it cool. Once cooled to 70°C pull hard. Repeat until pulls show no black. Or, if your nozzles are cheap just replace them. 

Note next time this happens, turn the hot end on so you can remove it quickly. Sounds like you chipped away.