Not sure if anyone has really determined the root cause. I have been using Lucas synthetic gear oil the additives may look a little milky. I regularly flush out the cavity with fresh oil before change and change it often. I doubt whether the water blast is the cause. Maybe add new oil and try it again and see how it is.
I'd say the first thing to do in such a case is checking if the breather hose is still attached properly. The hose is not secured and can rather easily become detached without being noticed.
