I've had a problem with my UH7760NB since I bought it 6 years ago. Should have returned it under warranty, but it's too late now. This radio has a speaker in both the base unit, and the microphone. In reception, the audio seems to oscillate rapidly between the base unit and microphone speaker. It makes reception almost impossible. The base unit is hidden deep under the carpet floor, so the base unit audio is muffled. Any ideas how I can fix this? Is there a service manual with circuit diagram?