I had the same problem. Just do the BFO Calibrattion explained in the original manual.
3. Setting the BFO
- Click on the encoder button to display the menu, rotate it to the “Setup On?” and click on to confirm it
- Tune to an clean and preferably weak SSB signal to its loudest (not the clearest)
- Click on the encoder button again to display menu and choose Theoption ‘Set the BFO’. Click to enter this option
- Now tune with the encoder for the best sounding audio
- Press PTT to save the calibration.
Done. 73 Mike KF6KXG