I'm going through the flight test with my printer and when I try to extrude the ABS, I get a clicking noise from the extruder and the gear appears to be skipping. The plastic still goes down, but it's a bit herky-jerky rather than smooth. In case the nozzle was clogged, I tried to empty it, but the clicking persists. I'm not totally sure I unclogged it correctly though - a video of how to do that would be helpful. I also cleaned the grooves in the gear to no avail. Is there anything else that could cause this?
I haven't tried the PLA yet, but will just to make sure it doesn't have to do with the ABS sample being too large a diameter or something like that.