I am having a problem on my 1974 MF20 industrial. I am getting a bad leak of tranny oil out of the weep hole on the bottom of the tranny case and through the expansion plugs. It is a pretty good leak. I have been topping it off with oil. Prob went through 3 gallons in 15hrs of usage. After checking it and seeing it was up to the level on the stick a ran the tractor. An hour into working I heard and felt a binding in the tranny. I shut it down right away and checked the oil level. It was fine. I can't figure why it is leaking so bad and why it went bad while I had the fluid level topped off. Any help here would be greatly appreciated.