Like something out of Hammer House...

Have you checked the drain run? Is it in copper ( like mine ) or cast iron? Where is it discharging? And exactly what is bonded?

And yes - check the neut terminal, main earth bond and PME. Look for no-volt on the PME path ( needs a temp rod unless there is already one in ).

Bizarre!! [Linked Image]

If hindsight were foresight, we'd all be millionaires!