In my repair shop I realize modification and improvement of instrument keywork too.
One of these is the realization of the automatic for the opening of the G sharp on instruments do not yet have such a mechanism. I have implemented several variants of this automatism, trying to get better and better the response of the instrument and the lightness of the command.
Below you can see some examples of such changes made on Buescher True Tone the years 20-30. We can make this change on any instrument that does not have one.