I recently purchased a Retro 51 Tornado fountain pen, in Lincoln of course, and I was wondering if anyone knew if I could change the nib out. I do like the nib it came with, but I was wondering if I could swap it out for a stub nib or something. Does anyone know if this is possible and what size would it be? I was thinking it was a #6, but I'm not sure and don't feel comfortable trying to yank out the nib just yet. Thanks in advance!