I have a Kubota B3300SU with a BH77 backhoe. A few weeks ago two of the valves had to be rebuilt. Now the backhoe looses power when it gets warm. Mostly when clawing the bucket. I check the fluid and there is none on the dip stick so I top off the fluid. After using the backhoe for about 15 min the power is gone again and so is the fluid. I also get a jerking in the arm when raising or lowering it. I have checked and checked and checked some more but can not find a leak anywhere from front to rear. Any one have any idea where the fluid is going?