As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK: NR 1 ENGINE HYDRAULIC LOW PRESSURE LIGHT ILLUMINATED IN FLIGHT. REMOVED AND REPLACED NR 1 ENGINE HYDRAULIC PUMP IAW B737-400 AMM 29-15-11. OPS AND LEAK CHECKS GOOD. NOTE: PART IS "ON CONDITION" THEREFORE TIMES AND CYCLES ARE NOT TRACKED.