T0-30 3pth won't lift

I have a Ferguson TO-30 with a 3pth that stopped lifting with a load the other day. It will lift by itself and with me sitting on it but not with any implement attached (NH 451 mower, rear end bucket, etc). I checked the gear oil and it was old and had some water so I replaced it and now it tries to lift (jumpy) but will not get off the ground. When I changed emptied out the rear reservoir below the hydraulics there was a small amount of rusted bits of metal caught in the drain plug which has me slightly worried it"s more than a small problem... Any thoughts on the culprit? Thanks in advance for your help.

-Bob

Update: Further inspection of the 3pth lift arms showed one arm was severely worn out due to a loose nut at the base of the tractor and twists when it tries to lift. When I detached that arm and attempted to lift an implement with only the good arm attached the tractor lifted it without a problem. Perhaps replacing the worn arm will resolve the lift problem? Or perhaps there is a busted seal on the same side as that bad lift arm? In any case I'll be replacing the worn out arm tomorrow and will let you know if there is any improvement. Thanks again,

-Bob

Most failures to lift are the result of a badly leaking hydraulic system, or a stuck control valve.

With tan implement on the hitch,remove the side plate and with the engine running and the PTO engaged(UNDER NO CIRCUMSTANCES PUT YOUR HANDS INTO THE HYRAULIC COMPARTMENT WITH THE ENGINE RUNNING1), pull the lift lever completly up and look up toward the seat to observe the lidf cylinder. There should be no oil coming from it other than an occasional drip. Using a mirror and flashlight look into the front right hand corner of the hydraulic compart for a vertical tube the supplies fluid to the liftcover/ lift cylinder. Is the fluid streaming from the tube? If there is it"s leaking.
next move the lever down and then up and observe the "H" shaped control arm move back and forth to actualted the control valve submerged in the fluid. the lower part should move smoothly forward to lift and smoothly backward to drop. Listen for noise and a lot of turbulence at the aft side of the pump. This could indicate a spartialy stuck open releif valve. Similar observation around the pump side plates are indicative of a blown pump side plate gasket.

Finally,with the engine shut down, reach under the oil surface at the lower part of the "H" shaped control for and feel around fro the "T" shaped control valve stem. mae sure it is attached to the control fork and then slide it orward and pull it aft. It should move about one inch for full travel from full back to full front and should feel smooth.
Do these checks and you be able to determine what the problem is.

O.K. Thanks Jerry I'll perform those tests as soon as I get the chance and let you all know what the results are. Thanks again!

-Bob