As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HF1 RADIO RECEIVER IS GARBLED AND UNUSABLE ON 4 ATTEMPTS WITH DIFFERENT FREQUENCIES. HF2 XMITTER AND RECEIVER NORMAL OPS. HF1 HAD FADING ON SFO ARINC BUT WAS SOLID RECEIVING WWV UNABLE TO VERIFY DISCREPANCY. REMOVED AND REPLACED HF NR 1 RECEIVER IAW MM 23 11 21 AS PRECAUTION. VERIFICATION FLIGHT SUCCESSFUL.