If my fretless fingerboard became grooved and worn out can it be replaned or should it be replaced?
It can be resurfaced by sanding, and could be replaced by a professional luthier. Resurfacing the board should only be done when the wear is sufficient to cause the sound or playability of the instrument to suffer. Resurfacing too frequently will greatly reduce the useable life of the fingerboard. Usually, replacement is only necessary after several resurfacings and years of heavy use.