I just bought a used 1986 Agri-Power 5000 (Zetor 5211) with cab and front end loader, and have been peforming oil changes and level checks as per the manuals . The tractor has 1300 hours on the engine. I have found the oil fill plug for the steering box that is located inside the steering wheel console at floor level. The operating manual calls for 1/2 gallon of gear oil. Is there a drain plug on the steering box, and if so where is it located? Is there a level check plug also? Thanks.