Piston seals leaking or clutch plates slipping in range involved.

Overhaul the transmission.

Refer to applicable Allison Transmission Service Manual.

Forward clutch piston seals or clutch plates slipping (all upshifts).

Overhaul the forward clutch and the piston assembly.

Refer to applicable Allison Transmission Service Manual.

Damaged front support hub seal rings.

Replace the rings.

Refer to applicable Allison Transmission Service Manual.

Sticking governor valve.

Clean or replace the governor.

Refer to applicable Allison Transmission Service Manual.