My little '63 D-10 has a problem with either weak or just plain lifeless hydraulics after about an hour, give or take depending on work. Basicly, all we do is run a box blade to drag our roads and maybe push some brush. The tractor will raise the box blade pretty well until it seems like the tranmision oil warms up or something. I did a full service this spring. Drained oil from every plug in the service manual and went back with oil as the manual advised. Changed all the filters too. Still, the problem is there. Talked to an older man about his Ford and he says his does the same thing. Is this just normal or is the pump getting too much wear to pump warm oil...what's going on?