Jack, can you give us a little more information please.
1) Does the tractor move at all in any gear?
2) Have you gotten a pressure reading from the rear remotes? If so what is the pressure. (you can screw a gauge into a ISO tip to get the reading)
You really need to have a flow test done to isolate the problem. I donít know what it will cost you but itís worth the expense. Otherwise youíre guessing and with the high price of parts a bad guess is expensive.
That said my first guess is a possible charge pump failure. Itís serviceable without splitting the tractor.(underneath the tractor where you changed the filters)
Itís also possible to have a main hydraulic pump failure and cause a similar problem.
Even a bad/slipping torque limiter clutch can cause a similar problem. (means a front split, not as bad as it appears)
On my 1370 the C4 clutch failed plugged up the internal screen and caused a similar problem. (Letís hope thatís not your problem.)
P.S. you can rig up a set of test gauges to test the Power shift. I bought 5, 300psi gauges mounted them to a piece of angle iron then attached 7ft long ľ hoses to them. The hose had a fitting to connect to the gauge on one end and a jic male end on the other that screws into a 1/8 swivel adapter to a corresponding port on the cover plate for the power shift.