I have a Autojector HS-30 machine which does not turn the screw fast enough. The hydraulic motor turns the screw fast without material being fed but once material (Flexible PVC) is fed, the speed decreases to about 40rpm. My thinking is that either my hydraulic pump is not getting enough volume to the motor or my screw is very dull. (I'm leaning to the first.) Any ideas would be appreciated.