I recently discovered I have quite a lot if moisture inside barrel of my M400 (behind piston in the shaft area). I have this pen for about 2 months now and cleaned it ca 4-5 times - with nib unscrewed and pen body under water tap.
Is the connection between filling knob and barrel supposed to be watertight or is this normal? Problem is on M400 the piston part cannot be easily removed, unlike simple unscrewing on M800 so I cannot simply wipe it with paper towel.
Do you have any proven methods or suggestions how to get rid of it? Leave the pen with filling knob fully unscrewed for few days maybe?