What's most needed is for the person who put the guitar peg on the peghead to be taken outside and fed to the crocodiles. Its a fine antique banjo. If it was mine I'd replace that odd peg. If you or your luthier can't find a matching old one, replace all four with some good modern ones, eg Waverleys, and store the old ones for posterity. I've seen a lot of banjos but I don't recognize that moveable thingy - Maybe it used to hold on a scratch plate?

Cheers
Ray