If the ends of the frets protrude from the fingerboard, playing gets more difficult. This can occur as a production error, but also if the fingerboard has warped by changes in humidity. For repair, it is recommended to use a cheap nail buffer with different sides. First, cover the body where the fingerboard merges into the body with a piece of tape. So it should be avoided to accidentally damage the body with the buffer. The coarsest surface of the buffer is now passed four to five times along the sides of the fingerboard to sand the waistband ends. If they are still sharp, repeat this process. Finally, the frets ends are smoothed and polished with the finer surfaces of the sanding block.