I am working on a Ford 8670 that has 5,000 hours. It has sat in a shed for about 5 years. When we got it out to test drive it everything was good. The next day the owner drove it about 30 miles. About halfway the Hydro filter plugged light came on and once he got to his destination the brakes quit working and now the reverse is not working. I have changed the filters and oil and have also cleaned the sump screen. I have also cleaned a few screens in the control valve. I am getting 250psi on the Rev port on the side of the transmission. The local mechanic is telling me it's the clutch packs needing replaced. what ports do I need to hook up to see if it is actually leaking by internally? Thanks!