As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO TRANSMIT ON HF#1. WE CAN RECEIVE ON BOTH HF#1 AND HF#2. TRANSMIT ON HF#2 AND GOOD SELCAL ON HF#1 AND HF#2. SATCOM WORKS GREAT. GROUNDED - YES. REMOVED & REPLACED #1 HF TRANSCEIVER PER B737-9 AMM TASK 23-11-21/401. OPS CHECK GOOD. SIDETONE AND TONE OKAY.