Hinged Flanges

[A. Carl Eisenstadt]

Hi,
    A customer wants me to rebuild an 1839 Daniel Thomas square grand.
All of the flanges, both hammer and jack, are hinged with what looks like
parchment. 
    How can these be rebuilt? What material should be used? How do you get
the old material out? What is the best way to replace it?
    Any advice would be very appreciated.
                            Carl Eisenstadt