Hi, slogging through some issues in my mid-90s-but-new-to-me aircraft. Working an electrical problem, my mechanic and I were puzzling over this. Does anyone know the purpose of the mercury switch listed in schematics between the voltage regulator and alternator in Super Decathlons, at least older years? Haven't traced wires, but I think it's the small blue cylinder on firewall next to Christen inverted oil unit. Thanks!