Any of the following: Cannot change band to UHF, no UHF volume or squelch control, no UHF tuning, or strange-sounding beep tone.
Rework bad soldering at J3 on display unit and replace the SW-B board with a factory-modified flex PC board.
No audio output from receiver.
Remove excessive solder on the Main-A unit near the audio amp.
Howling if volume is turned up when using UHF.
Microphonics in VCO section. Resolder the ground spring at the UHF VCO shield. You may also add a second spring for further improved resistance to microphones.