Just picked up this 601, the previous owner thought for sure the hydraulic fluid in bell housing was coming from the pump (which didnt make since to me since it runs off the cam gear) and he had the pump rebuilt. I installed the rebuilt pump and fired the tractor up only to find (as i suspected) it was still leaking hydraulic fluid in bell housing (more like pouring) and it pour out the timing hole. I know there are two O-ring that go from the pipe to the transmission but logic tells me if those where leaking wouldnt it leak on the outside rather than on the inside of the transmission housing or are those O-rings far enough inside the transmission housing enough to leak there? Or do you suspect i need to split the tractor and go from there. I am not familiar on how the hydro pipes through the transmission so any information you have would be great. The service manual I have shows the diagram on how it works but not enough detail to what the pipes look like.