Now's the time to weld it while it's out of the piano -- you can't
weld it when it's in the piano.  Get a good welder, though.  There's
no stress there at the honeycomb, so the weld is only for show.

We welded the plate of a grand piano, cracked on the right side.  The
welder put in big piece of metal, so hard I could not drill it.  When
the plate cracked in the middle we decided to throw the piano out.

Wayne Boksa