I'm interested in this piston filler but I'd like to know if the nib comes out for easy cleaning?

EDIT - oops. wrong forum.

I will defer to the experts, but I am pretty sure that it does not thread out like a Pelikan.

I have removed the entire nib 'section' for cleaning, and although I did not do so, you probably should get the special sap-like sealant that OMAS uses in order to properly reseal it.