gear box leaking

I have a leak from a black disk behind the gear shift, the disk turnes, should it? can it be sealed or is it a breather, if not where is the breather. Thanks

The breather is further back. I sealed mine up cos mine was leaking as well!

how far back is the breather?

Its a small hole in the steel plate on the highest point of the gearbox, the plate sticks out either side of the seat box. I've had my box apart today and the gearbox/transfer box seal was leaking so the transfer box was full up! I'll tell you if a new set of seals solves the problem!!