K2 owner here for 18 days and CR10sPro owner for 4 years. Zero problems setting up and running the K2 (mainly using PLA without glue) so far but yesterday had a massive blob the likes of which I have never seen before while printing regular PLA . There was a error message on the screen but it was still spewing out filament when I came back 50 minutes later to check, to find the print failed to adhere to the bed and it looked like this.
I had to partially dismantle the head but fearful of over heating fan housings connectors, circuit boards etc I decide not to apply heat to the blob with a hot air gun instead I heated a box cutter knife blade and slowly hacked away enough of the blob to remove the hot end.
Then I was able to apply the hot air gun (this time an SMD heater) and finally managed to get the blob off the head.
All up this took about 2.5 hours.
Next I tried to remove the nozzle (somewhat foolishly without heating the holder) and snapped off the tip. I’ve removed nozzles on the CR10 when used with PLA before without heating but did not realize the copper nozzle would be so soft.
Anyway I managed to get the threaded section out easily (almost by hand) by applying heat with the SMD heater and using a 3mm easy-out left handed screw remover.
Luckily I had a replacement on hand.
A small but useful benefit is I now know how to remove and replace the hot end 
and even tackling such a mongrel of a blob. I’m now concerned if it was to be a higher temp plastic although these seem adhere better to the PEI plate than PLA. Am now using it with glue.
I have to admit I was surprised the K2 let things get this far. Just wondering if anyone else has seen a K2 with such a massive blob?