Tractor Repair: IH 574 diesel, filter canister, loose power

Question
I recently changed the hydraulic oil on my tractor. After i changed the oil, the hydraulics would not work. I bled the lines thinking it had air in the system. It started working but now when i start my PTO I loose power string. I stop the PTO and it works find. I also notice that the shift handle is hard to engage or disengage the PTO. Any help would be appreciated.
Thanks Adrian

Answer
  If you changed the filter also, it's possible that the filter canister is not seated properly into the groove and the pump is sucking air.  The lever being hard to engage is not related.  Lubricate the lever pivots and linkages that run behind the seat to the multiple control valve.