Montblanc runs a nib workshop within its own customer service department, which tunes nibs to the individual writing style; what is adjusted is above all line width, grind and ink flow, in other words the position and shaping of the iridium tip in relation to the way the pen is held and how hard the writer presses. In the mid-2000s this department was headed by Wilfried Ross. As matters stood then, the service was open in principle to every customer and was not restricted to bespoke work; the cost and the turnaround time can be had from customer service or through a specialist dealer who sends the pen in.
A nib that is only slightly scratchy can also be smoothed at home. The usual method is very fine abrasive paper or micromesh, on which the nib is moved with light pressure in the normal writing position, a little at a time and with frequent test writing, since material once removed does not come back. With old and valuable nibs, with tines that are bent or sitting unevenly, and with slits that have sprung open, a specialist workshop is the safer route, because there the alignment of the tines is corrected first and grinding follows only afterwards.