Flhouser link to service manual subtly shows on page 9-7 that hole which is the vent for the gear box. It will weep a little during normal use but will weep A LOT if you overfill the box. This is something most of us have done because you do NOT fill to the fill hole. That manual also specifies how much oil should be used. I recommend you drain and refill with the correct amount to be sure.