TM 9-2320-361-34 15-36. INTEGRAL DERRICK MAINTENANCE (Contd) b. Inspection Inspect derrick tube (5) for bends, breaks, cracks, or flat spots. Straighten minor bends. Replace if derrick tube (5) is badly bent, broken, or cracked. c. Installation 1. 2. 3. 4. 5. Apply a coat of GAA grease inside base (2). NOTE Assistant will help with steps 2 and 3. Slide derrick tube (5) over auger rack bar (8) and into base (2). Aline sighting hole (6) to face three screws (3). Tighten screws (3) and new locknuts (4) on base (2). Retract auger rack bar (8) into derrick tube (5) (TM 9-2320-361-10). Return derrick (7) to resting position (TM 9-2320-361-10). FOLLOW-ON TASKS: . Install derrick sheave (para. 15-37). ● Install earth boring machine seat and backrest (TM 9-2320-361-20). 15-127