The control valve is stuck or inoperative.

1. Clean the control valve.
2. Inspect the control valve.
3. Replace as needed.

The pump ring is extremely worn.

1. Inspect the pump ring.
2. Replace the pump ring as needed.

One or all of the following parts are scored:

1. Inspect the components.
2. Replace as needed.

Refer to End Plate and Rotating Group Replacement .

The pressure plate is broken or the thrust plate is broken.

Clean, inspect and replace components as needed.

Refer to End Plate and Rotating Group Replacement .

The vanes are sticking in the rotor slots.

Clean, inspect and replace as needed.

Refer to End Plate and Rotating Group Replacement .