Most likely the seal on the draft control signal rod is leaking. You can test this by removing the PTO assembly and then look for oil leaking by the signal rod. Now here comes a second thing to look at. If your tractor is one of those 1800 models that had a hole drilled in the transmission case so the oil would not transfer from the rear to the front transmission case or the other way your front seal on the hydraulic pump could be bad. No doubt Boellners down the road in Maumee will have all the parts you will need. More questions?