I have what might seem an odd first step suggestion for grand regulating: Pre-lift wire. This is a strategy to end up with no underlifted strings.

When a piano is newly strung, the steel wire, being stiff, takes rounded curves, not corners, as it passes bearing points. Each time the wire is pitch-raised it refreshes these curves a little, particularly at agraffes and Capo D’Astro bars. A conscientious technician will settle the wire and mate strings with hammers, a process well-known to us all. Touch hammer to unison strings, pluck the strings, and if any ring, lift the others with a stringing hook until all are equally muted.

A question left in reference to one of my videos on hanging grand hammers finally receives a response after 2 years languishing unseen on YouTube. Come on, Chris... Q. With an uneven string height, did you then change the bore distance incrementally as you drilled the hammers?   A. An important question. String heights are often not parallel t...