I didn't take any 'before' photos as there was nothing wrong then.With my lack of good scope experience I'm always wary of what I see under fault conditions, that's when I wish for a "before".
The basic U3S PA is so simple that given a good input waveform there seems little to go wrong. All it needs is a steady supply voltage and good joints.
The photos are there now, I hope someone has the answer.
output voltage before was around +/- 8V peak to peak sinewave for most of the lower bands. Now it is lower and distorted.