Hydraulics problem

My old 743 skid steer seems to be leaking hydro fluid into the chain case. Is this possable? If so, where should I look for leak? Short History. Bought machine this summer. With no history, decided to replace all fluids, and filters, and put new seals in lift arms and tilt cylinder. When I opened the chain case it was FULL to the top. I thought that was wierd but possable. drained fluid cleaned case and refilled with fluid (5W/40). I am now losing fluid,but have no drips or visable oil leakage Any help or advise would shre pe appreciated

Your going to drain your fluid again and pull the drive motors and replace the seals in the reduction box once you ge the seal out take out the big steel washer and put a new quad ring in you will also need new orings for the drive motor go to lowes and buy a pvc coupler to fit the seal with a square screw in plug to set the seal do both sides should be under 50 bucks in parts from bobcat

Mine had the same problem - no visible oil leak but TONS of oil in chain case - 12 gallons actually. You may have already done this but we raised the machine using the bucket, put jacks under front and back, removed the front wheels, removed the access plates for the motors and the other cover, raised the cab, climbed inside (need very small person) and cleaned and dried every single thing in there. We lowered the cab, added enough oil so it was visible on the dip stick, used a really strong flashlight, lay down outside far enough away to be safe and raised and lowered the lift arm. NOW the leak was visible. If everything is wiped clean and dry you can then raise the cab again after you have equalized the pressure and you can see the path of the leak and get a much better idea where it's coming from and go from there. Mine was the test port hose leaking gallons. A pain to get off and replace but so far no more leak. Good luck.