The clutch is slipping in one range.

1. Rebuild the specific clutch that is slipping.
2. Replace the piston seals.

Refer to Allison service manuals.

Oil is leaking excessively at the piston seals in one range.

Overhaul the clutch and piston assembly. Refer to Allison service manuals.

Oil is leaking in the valve components of one range.

Replace or rebuild the control valve body assembly. Refer to Allison service manuals.

The trimmer valve is stuck open.

1. Replace or rebuild the control valve body assembly.
2. Check the trimmer valve for freedom of movement.

Refer to Allison service manuals.

The priority valve is cycling.

Replace or rebuild the control valve body assembly. Refer to Allison service manuals.