Quite a number of pens come into my shop with the original tipping in good shape, but just needs careful, special contouring of the tipping to restore the smoothness of the nib.
This early Onoto pen came all the way from Australia and after a few hours of close up, detailed and skilled hand working of the tipping, it is now in much better shape then before.
You will note the before photo how the nib tip has a “flat foot” while the after shot the tipping is rounded. Takes steady nerves and lots of magnification to do this job properly! Forget about those emery board treatments or those cloth smoothing sheets; you will just ruin the tipping in the process and then I will have to retip the nib for you! Trust me, I have done many retips after the pen owner as tried to “fix” the nib themselves.