Hello, Keith.  You're probably quite correct about the deposit being
lead carbonate, rather than lead oxide.  I'm no chemist!

My reason for replacing the tubing in my Autopiano action had little
to do with the deposit (although that would have been difficult to
remove from the interior of the action), but rather had to do with the
multitude of pin holes the corrosion had caused.  At the time, Player
Piano Co. still supplied the beautifully-made adapters that allowed
an almost direct replacement of the badly corroded lead tubing with
Neoprene, requiring only sealing the adapters into the wood with burnt
shellac.

Bob Loesch