Bad Link Cable Connections - soldered them direct to valve PCB pins - and Missing Tube Heater link cable.
Probe slip arc'd heater feed caps - blew mains LED cct. Used valve LED. Lost speaker output. MP3 and 1 channel for guitar in works via phones.
Tube heaters now working so have pre amp:
Some overdrive waveforms are interesting. Max clean channel "sine" before distortion etc:
