[BILL]

I say the problem is in the power supply , did you replace the filters? and I assume you've changed the buffer , check for a shorted 0Z4 tube socket, and the power transformer that one is not all that easy to replace, it is sodered in to the chassie, and is the 0Z4 any good ? I no longer use original 0Z4's, You will have to check thing out with power on your power upply as the B voltage with jump,watch the tube socket for arcking, check for waxs heating on the transformer, sometimes the vibrator hash choke ,has enamal wire can get bumped and short to chassie