The ORS (over riding solenoid) in the governor is what allows oil flow to go to the load regulator increasing excitation. When it is energized the load regulator stays in the minimum field position, when it gets de-energized it allows oil pressure to flow to the load regulator, bringing it to maximum field. The power for the ORS is a rather simple circuit so you should be able to check it pretty easily. It should be a PC wire (positive control) going to a NC (normally closed) interlock on the BF contactor, then it goes to the governor, only making stops at terminal boards. Every time you pull the throttle out BF lifts, de-energizing ORS so the load regulator can start slowly coming around for a smooth increase in loading. If the interlock on the BF is starting to fail it can intermittently not make a good connection when it drops, therefore not giving juice to the ORS, therefore keeping the load regulator at maximum field. A couple more cycles on the BF and the interlock makes a good connection and it all goes back to normal. That’s a typical EMD setup. Hope this helps!
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