I really don't think this suffices as a thorough explanation and based on this do not think it could be responsible for seeping.
And "a lot of stress" is not really quantifying it. The shafts are slipped more than 2" into the casting and welded in 3x holes so it can't slide or rotate. It's not like they are butted up against it on the outside and welded around, where this type of lifting would clearly be trying to shear them off the housing.

I just don't think this kind of unsubstantiated guess is adding to OP's issue or thread. But I am eager to hear otherwise.