I removed sump case from engine block on workbench with shaft pointed towards me in horizontal plane to install new sump case gasket. Now engine revs dangerously high when starting mower. I checked carburetor linkage already and it appears correct. I was not sure which position the governor should be in so I tried it both ways - full clockwise and full ccw and engine still revs to the moon upon start up. Is there something internal to the sump that may have shifted while the case was separated from engine block? Could carb jet be stuck open since block was laying on its side? Other theories?

Thanks, Paul