We have lift-off, well taxiing anyway.
After changing a couple of transistors on PC128, all PSU voltages are now about right and I can get both traces on the screen; I can even get a waveform display, from the +1v Square wave output under the CRT, though it's a bit fuzzy.
As regards the other two outputs from the Right Hand amp, neither will display on this scope. The sawtooth however will come up on a different older scope, but nothing from the square wave output.
On/off switch works, but the intensity pot doesn't seem to have any effect.
It's a start anyway, though I had to knock off for the evening when the macaroni cheese was served.