I have a black MK30 which I got off of Ebay. The pen writes wonderfully; my problem is with the piston fill. Turning the piston is difficult because it is so very tight. Being unfamilar with the pen, I am reluctant to force anything. Is there an easy/correct way to take off the nib so that I can lubricate the piston for easier filling?

TIA,

William (Neophyte Pelikan Lover)