Very first stop; check the back end oil level.
You need to find what state it needs to be in to check the oil level, usually it's engine off and all rams in lowest position BUT I know some tractors you check with the engine running, then the oil level is above the sight glass when the engine is stopped and I've known people set it by the sight glass which means it's too low when running.Went out for a look see. Oil level glass hard to see but level there
did it stop working whilst you were using the the highbollicks or did you stop it and then it would not------re hydraulicise ---after the restart ?then after say an hours running so everything nice and hot, they are not working again.......