We received a good restoration hint from Charles who is rebuilding a turning motor for the Bayport Aerodrome, New York. He normally works on player pianos. He recommends replacing old leather nuts with plastic ones. Charles says that leather nuts supplied today are full of acid and he has had steel threaded rods destroyed in less than 10 years by them. He recommends plastic nuts with a ¼” hex head which look something like a leather nut.
They are available from Klann Organ Supply, www.klannorgan.com . They have a #50 center hole and will go on to most small threads. They tend to crack if the thread is too big so it is best to drill out the center hole to about 0.010” under the outside diameter of the threads you are going on to. #50 = 0.070”. A tip of the hat to Charles.