Hello,
My k2 is making some honking sound. Have printed for 9 days and a couple of hours. The last 3 models it started. Never had jet before. Its not only the model currently printing. Anyone got a idee where this sound is coming from ?
Hi, I‘m also having that issue. Not permanent but from time to time. My impression was it‘s somewhat depending on the model but I’m unsure and I didn‘t find any systematics yet. It sounds like a little bird is whistling from within in my K2 Plus… 
Left and right near the pulley of the belts there was a lot of dirty grinding with some iron. something to keep an eye on in the future. Have learned if something rubs it will break once.
I lubricated the rails with oil. and cleaned everything. now with the same file much less noise.
don’t hear it anymore in the bedroom three rooms further that is and six walls in between