Last time I worked the tractor hard mowing meadows the hydraulics quit working, the tractor was not hot but after a lighter load the hydraulics started working again. Both the remotes and the 3 point quit. Not low on fluid, the transmission was full. No problem since then. Power steering is a separate pump and it has worked through it all. So, I changed the filter today and it took 15-20 minutes of running before the hydraulics started working. Remotes and 3 point are working fine now. Any Ideas?