Cooled-down and cured filament from filament loading sticks to noozle  

Cooled-down and cured filament from filament loading sticks to noozle

I am new to 3D printing and have successfully assembled my Core One. Everything has gone smooth so far. Problems started when I tried to calibrate the filament sensor and during my first test print (the keychain).

When the printer loads filament it squeezes out some of the filament and asks me whether the color looks right. That part of filament cools-down, curses and does not fall off, i.e. it remains stuck to the noozle. The printer drags and pulls that short string of filament around during printing. The issue is reproducible and consistent.

I run into the problem the first time, when I calibrated the filament sensor during the initial setup. The material which the printer squeezed out remained on the noozle and interfered with bed levelling during the next step.

During my first test print the material remained on the noozle after filament loading and was dragged through the first layer.

My second tesr print was the two-color version of the keychain. When I changed the filament and the printer asked me whether I see the correct, new color, that hard piece of filament remained on the noozle.

Each time, I had to open the door and remove, i.e. pull off, that colled-down, hard piece of filament with needle-nosed pliers.

What's wrong here? I don't believe that this is "stringing", as far as I understand, "stringing" seems to be something different. For me as a beginner it seems as if the printer fails to "shake it off", if this is actually a thing.