Hi all, Kim Bunker here from playerpianos.com.  Repairing a cast iron
plate is next to impossible. The reason for this statement is cast
iron piano plates until the introduction of the V-Pro process injecting
plastic into the mold before releasing the iron by Yamaha.

All piano manufacturers used wet sand-cast molds and when the iron
cooled it generally had imperfections throughout the process.  This
particular iron is loaded with carbon to help with its strength after
the piano is strung with piano wire.

Generally it is under a minimum stress factor of about 7 tons.  For
illustrations and more information refer to my scale information on my
web site:  http://www.playerpianos.com/scale1.html

The reason for this explanation is to show you that when this stress is
applied perhaps you'll understand that the only other metal that could
work is sometimes nickel, because nickel will stretch with iron and has
a more elastic molecular structure.  We have for over 30 years tried
many methods and found that braising with nickel was the only one that
worked and not all the time.

Kim Bunker