Luxman going out of phase

John thanks again, for your patience as well.
You're welcome. BTW if you do look at all three wavforms, you will see both the output traces moving in phase relative to the reference waveform being used for the trigger. The important issue is not that the phase changes (it has to or the tone controls won't work 🙂) but how much variation there is between the channels. A significant variance (say more than 10%) could indicate a fault, or just poor tolerance of the component values.