TM 10-3930-671-24 Troubleshooting Guide Trouble Probable Cause Remedy 1. Oil leaks at either end of spool 1) Defective O-ring seals. Replace O-ring seals. 2. Spring-centered spools do not return to neutral 1) Broken springs. Replace springs. 2) Entrapped foreign particles. Clean system and valve. 3) Bent spool. Replace with new spool or valve section. 4) Misalignment of linkage. Check linkage for binding, repair. 3. No motion, slow or jerky action of hydraulic system 1) Relief valve not properly set, stuck in place and/or worn. Clean, repair, readjust. 2) Dirt or foreign particles lodged between relief valve Disassemble, clean and reassemble. control poppet and seat. 3) Valve body cracked inside. Replace valve section. 4) Spool not moved to full stroke. Check travel, linkage. 4. No relief valve action (high pressure) 1) Small particle of dirt plugging orifice in relief Remove relief valve and check, clean hole. valve subassembly. 2) Relief valve sub-assembly installed backwards. Disassemble, install correctly. 5. Load will not hold 1) Oil bypassing between spool and body. Replace valve. 2) Spool not centered. Refer to above spool remedies. 3) Oil bypassing piston in load cylinder Repair or replace load cylinder. 6. Load drops when spool is moved from NEUTRAL to a power position 1) Dirt or foreign particles lodged between check Disassemble, clean and reassemble. valve ball and seat. 2) Scored or sticking check valve. Replace poppet. F-463 (F464 blank)