I would really dig in on that generator wiring since it had gone out for repair. Some Otis gens are extra complicated and it helps to have the end diagram for the particular unit. This sounds similar to an issue we had after a rebuild. Found 1 field pole wired backwards, may have been in the leveling field, been a while. I’ve also seen one come back with neutral so far out that is wouldn’t level down. I make it a habit to set Neutral myself when we get a generator back.
