[sowise]

This might be stupid I don't know but I looked over your list and saw you pretty much had checked EVERYTHING else I could think of already. I am wondering if it is possible that your belt is or could be slipping on the pulley when there is a hydraulic load. Either more tension is needed or a new belt. Other than that if your pump is spinning and you have bypassed and checked everything like they are saying it should be a straight up fluid in fluid out kind of deal.