There are many ways to control a "shuttle" & most "electrical people" will achieve the same result in different ways.
You may be better off to buy a new unit from someone like Gaugemaster or Kent Panel Controls (or one of the other electronics companies) who all make simple to connect reliable units.
You may be better off to buy a new unit from someone like Gaugemaster or Kent Panel Controls (or one of the other electronics companies) who all make simple to connect reliable units.