[cathoderay57]

I think I have found the culprit - see pic. Tapping RV3 with a screwdriver reproduced the symptoms. On removing the preset from the board it measured open circuit between its ends and intermittent wiper connection. Replaced with a new one and all seems well (for now). Looking at the circuit RV3 affects the biasing of the whole amplifier chain since the transistors are all direct-coupled. When RV3 has an open circuit it throws out all the biasing hence distortion and loss of audio. Cheers and thanks for the advice. I hope I won't be back (with this radio, at least!) Jerry.