My 2cents... Leather has a very high coefficient friction and leather bushing are an absolute disaster unless are liberally treated with microfine teflon powder. Without dry lube the key plays a lot harder with a sideways glancing stroke and the bushings wear out and start to get noisy very quickly.... the same goes for cloth bushings but it is not as critical as with leather... You can test this easily by putting a little side pressure on the front key pin as you move the key up and down.... It takes a lot more force to move the key with a little side pressure if the bushing has not been treated with dry lube... David Stanwood
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