As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HF RECEIVES BUT UNABLE TO TRANSMIT SOUNDED BROKEN/UNREADABLE IN HEADSET WHILE ATTEMPTING. GROUNDED - YES. ACCOMPLISHED HF2 SYS TEST REF B737-900 AMM 23-11-00-730-801. ABLE TO DUPLICATE FAULT. HF2 NOT WORKING. RMVD/INSTALLED NEW HF2 TRANSCEIVER REF B737-900 AMM 23-11-21. PERFORMED OPS TEST HF2 OPS NML. REF AMM 23-11-00-730-801.