Norword Shelton
Sounds like your Hydro Check valves are leaking, not an uncommon occurance. Sounds like you have the later version with the self unloading if they have the hole in the top instead of the small pin.
First clean up the area around the check valves real good as you don't want to get dirt into the hydro. Take the check valves out, probably one at a time the first time you do it.
On the check valve there are two rubber o-rings and one plastic ring. The plastic one has a angle cut in it so it can be removed. Remove the two rubber O-rings and the plastic ring, remember the orientation of the plastic and the rubber O-ring. Inspect them and if damaged they need to be replaced.
Clean the check valve in a good solvent. I use a air gun to clean them, you need to get out any junk accumulated in them. I like to hold the check valve away from me and then shoot air into the bottom of the check valve. You will see the spring compress and the check ball move up. Do this several times, it is good to exercise them good and clean out any junk.
When you put them back together I like to assemble the rubber o-rings and the plastic ring and then dip them in Hytran before I put them back in the tractor.
If you haven't changed the hydro fluid and the filter it is a good time to do that and be sure and get the correct hydro filter not a car filter.
If they still leak you will need to get new ones from your Cub dealer or one of the sponsers. They are not cheap, I think the last ones I got from Madsons were around $95.00 each.