Whatever may be in the MMD Archives, I think most readers would agree
it is a matter of _application_ -- by that I mean _what_ is being
repaired.  If I am rebushing a set of keys, or re-gluing/replacing
loose/shot hammers, then I use hot glue.  If I am repairing a broken
action part, meaning something has let go in the wood, then I would use
a "modern" glue.

In other words, when doing something that might conceivably have to
be repeated down the road, or where the "feel" of the piano may be
affected, as in different absorption of hot/other glues in bushing
cloth, I use hide glue.

In other instances I do not.  The original builders of these used the
technology that was available.

Mike Haydon

 [ Likewise, the old man who built cabinets for 1920s radio receivers
 [ just wanted to "meet the specifications" and get the work out the
 [ door.  Same for the modern organ builder.  The restorer has a
 [ completely different goal -- to preserve -- and so he uses different
 [ methods, even if it's more trouble.  -- Robbie