This is my second rotary knob for my Ultimaker 2+ 3D printer.
This time with the Ultimaker robot in very good print quality.
Removing the existing rotary knob from Ultimaker:
Behind the existing rotary knob of Ultimaker there is a transparent protective housing, which is illuminated by the LED's. At the rear of the protective housing there is a small opening. With a screwdriver you can push the knob of the potentiometer through the opening.
But be careful, do not use a lot of pressure!
I have uploaded new pictures, which clarify the process.
Sorry for my bad English.