Musicians Roadhouse

Gentlemen,
I have another uncooperative Marshall on the bench,and without a schematic I am lost.
There is no output on any channel or power setting,and no pop thru the speaker when checking B+ at tube pins. There is B+ which rises a bit when switching from low to high power,other than that I don't know where to go next. Does anyone remember when amps were easy to work on?

On follow up there seems to be no filament voltage on the PI tube,all others seem appropriate.