For over a week I have not been able to get a successful print. First I kept getting various errors, mainly around Z1 and Z2 errors. If I got past these errors the filament would jam up and i would have to take the extruder apart and remove a piece of curled filament.
The first errors were caused by the failing strain gauge. I ordered it and replaced it. I then did another full calibration, it failed the bed leveling, I did it again and then it passed. Yea! If you have to replace this part, follow the you tube videos for step by step removal and replacement.
I then printed a quick 6 minute template print and it completed it. I then tried to print a cup holder that I designed for my sons new wheelchair. Twice it failed, filament stopped flowing in almost the same spot. The second time removing the clog, I noticed the plastic in the extruder is damaged. See pictures below. The slot below the gears is worn leaving an open gap that allows the filament to jamb. It is hard to see but the plastic has rough edges where a piece broke off.
I hope this helps someone else trying to get their K2 to print.