As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HF 1 TOO QUIET TO UNDERSTAND SFO. NO STATIC HEARD. HF 2 OPS NORMAL. GROUNDED - YES. REMOVED AND REPLACED HF 1 TRANSCEIVER IAW AMM 23-11-21-000-801 AND 23-11-21-400-801, OPS CHECK GOOD. THE AUDIO WAS NOTICEABLY LOWER WITH HF1, HAD SENSITIVITY FOR NR 1 AND 2 SET THE SAME. AFTER LRU CHANGE BOTH SYSTEM AUDIO'S WERE THE SAME.