"bob.martin" wrote in message
...

" and after lunch the problem had returned and this time is persisting
despite removal of the valve. I haven't yet tried the mains blast across
the pins as I'm not that confident!

e advice

Jim G7NKS


You can use a charged cap to "blast" the short, might be less
dramatic than the unlimited current behind the mains.. This
sometimes vaporizes part of the grid structure and affects
tube operation..

Pete