I bought a 1978 f2 yesterday and went to drive home today and could not get the combine to go into road gear. I can shift all thru the 3 forward gears, but when I push the ground speed adjustment lever forward there is no increase in speed. The hydraulic level was low so I added 303 hydraulic oil which is what I was told that is supposed to be in it. Can anyone help me with what I might need to check I think it is a linkage problem, but not sure how to be sure. The combine has been sitting since January waiting on a buyer. The reason I think linkage is an issue is it looks like the lever has been being pushed into the guard kinda hard and pushing it up for more range of motion.