oil out of gearbox breather

[toxic]

good morning guys. I've got a bit of a problem with my lastec finish mower. While using it yesterday it started spewing oil out of the breather. The oil was a bit milky as if there was water in it so I changed that, didn't help. Put a different breather on it, didn't help. Even put a 2 foot extension between the gearbox and the breather, but once again didn't help. I'm at a loss as to why it is doing this. The gearbox is warm to the touch but nothing out of the ordinary so it can't be a bearing that is failing. Looking for any help on this as I have 130 acres to mow this week and without this mower that's not gonna happen.
Thanks.