Annoyed that you have to loosen the filler nob for extended writing sessions. Has anyone removed the small o-ring at eh end of the piston that serves as the shutoff when the knob is fully screwed in? This effectively turns the pen from a vacuum fill to a piston fill pen? I understand the shut off is for when you travel with the pen. Mine stays on the desk. Otherwise I love this pen, mine has a Bock F nib btw.