CTL midi auto feature

[Nickc78]

I am in the midst of doing a repair to my CTL Midi because the power switch sheared off, I had to open up the 3 way switch so that I can repair the switch spindle but what baffles me is that looking inside the switch I don't see any difference between the auto setting and the manual setting, the switch is just a pair of spring loaded gates controlled by the cams on the switch spindle which are open in the off position and closed in both the manual and auto positions so I don't get how the machine could operate any differently based on the switch setting, anyone know how this actually works?

 

[woodferret]

The auto path goes through a current-sensing relay.

Manual path merely closes the circuit for the vacuum.

 

[Nickc78]

Thanks, but I still question how, in both positions it appears both gates are closed so how is the power routing to the relay any different between the two positions?

 

[Alex123]

Main switch produces identical result in both positions (just "ON"). It is the green knob itself that has a little magnet on the edge. When you turn to Auto that magnet lines up with a reed switch on the electronics board ...