Tractor Repair: JD 4500 3 pt hitch will not stay in position, piston seal, pt hitch

Question
I have a 4500 John Deere, the 3 pt hitch will not stay in position unless you hold the up /down lever in the full up position.Then the hitch stays up but in between is not possible.

Answer
Right under the seat is a knob raise the hitch all the way to the top and turn the knob to the closed position.  Turn off the tractor if the hitch goes down then you have a blown piston seal. It is going to require removing the rockshaft housing. It is a dealer repair. If it does not go down then you have a problem in valve which is also a dealer fix unless you buy the manual and feel like tackling that sort of job.