Garry, even if you sort the breather - once the gasket has leaked as bad as this and moved (and bits been pulled out by you ), you will not stop the leak until you remove cover and either use gasket or silicone sealer.
Also if using a proper gasket :-X, I'd suggest you smear a little silicone on the cover side at least (I do both sides) as this will help to mitigate any distortion of the cover (they are often distorted by pulling setscrews up too tight in efforts to cure leaks ). Pull them up nice and gently and evenly. The manual says Differential Cover Bolts 33Nm or 25lb ft. And don't forget that reinforcing plate between bottom pair of setscrews.