As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SELECTED THE GEAR HANDLE DOWN AND BOTH MAINS STAYED UP AND RECEIVED A GEAR DISAGREE. RAN QRH GEAR STAYED DOWN AND LOCKED WITH MANUAL EXTENSION. (FLT 4576) REPLACED MLG RUN AROUND AND BYPASS VALVE ASSEMBLY IAW AMM. P/N: 750004000-003 S/N ON: 328A S/N OFF: 797A, P/N: 750005000 S/N ON: 0994 S/N OFF: 0021