I'm missing something.
If I wire the switch like it says in the tm9-1879 and the installation flyer, the shunt is out of circuit when ignition switch is in position 2 (blackout) because power from the ignition switch terminal 1 activates the relay and opens it. When switching to position 3 (service lights) it de-energizes the magnetic switch which closes the contacts and connects the shunt field like normal.
If I have the wrong mag switch and it is supposed to be normally closed it would connect the shunt during blackout operation and also power up the service lights.
If the idea is to cut in the shunt in both positions and isolate both sets of lights coming on it wold have o be a normally closed relay and the wire from the mag switch must go to terminal 1 Of the ignition and. Also the the original connection from the generator s field to terminal 2.
I thought the goal was to enable the shunt in both positions and keep service and blackout isolated.
Has anyone checked the actual results of this modification?