On a recent purchase of a 841 ford tractor i am having hydraulic problems. I have posted about it before. I havent had to time to get into it very deeply, my weekends have been very busy for the last few weeks. This morning I had a few minutes before we leave for oklahoma city and I drained about a quart of brown gravy transmission fluid out of the fill line plug on the side of the transmission. So, when I pull the dipstick for the hydraulic fluid it looks like clear and clean oil, when I back the plug out of the hydaulic pump to prime the pump the oil comes out rather dark not as dark as the trans oil. I am afraid that I have a hole in the suction tube inside the transmission case. How can I trouble shoot this? can I drain most of the fluid of the transmission and see if I get alot of air ect ? I took the fill cap off the transmssion case and i can see alot of oil moving around with the tractor running while it is in neutral. I dont know if this means the hydraulic pump is pumping through a hole in the hydo tubes or if there is a counter shaft or something spining down in the transmission. I have ordered some part and will start working on it next weekend including draing all the fluids. Any insight and advice would be greatly appreciated.