PT is the weber model DH specs – I am pretty sure that the only center taps it has are the heater and high voltage and those are the two that I grounded. will check tonight.
i will also try your grounding scheme minus the plate (using a bus bar).
And yes, the amp hums with guitar in or out, it starts as soon as the tubes heat up and start amplifying.
plugging in the cable and guitar does not change the hum at all – tone wise or volume wise.
only cranking up to 12 makes the hum almost go away, but a white noise hiss also come on – but again, exactly the hiss you’d expect out of a cranked amp.
I appreciate all these continued responses!!