Mrhiggins, I will start out first of all telling you I know nothing about your cub, but hydro's should have some type of replenishing valve in it's circuit to keep hydraulic oil to its pump. If you can find out where it is located maybe it is as simple as taking it out,clean with solvent, and make sure it is able to move free. The pump and motor are a closed loop system so your other hydraulics as you metioned are o.k. and that would feed to your hydro pump as some one else mentioned. It sounds to me air is in there and it needs bled out or it will chew your pump up. Remember clean everything around anything you open very clean, 1 spec of dirt could have been culprit.