In regards to the grounding scheme, this amp presents a dilemma. If it were a scratch build or new prototype, the answer would be to simply follow the modern convention; i.e. twisted pair heater wiring, center tapped heater winding or artificial CT, follow Merlin’s advice or Rob Rob’s grounding scheme, etc… However, things were done a little bit differently at the ole Bell Air factory in 1953. Inside the painted chassis, the grounding is run via an uncoated wire, which is soldered to the base of each of the sockets in a more or less linear order from rectifier to first pre. They have run the heater wires with one grounded at the base of the recto socket, and one heater wire that travels down the line of sockets terminating right next to the grid pin of v1! At this point, one would be tempted to just remove the old filament wiring and install twisted pairs and an artificial center tap. The only problem is that the point to point layout has utilized almost all of the extra socket pins as additional solder lugs. In order to “correct” the filament layout, one would have to redesign the rest of the p2p layout. Yikes! At this point it becomes obvious that we should just roll with the original design, get it fired up and listen to assess if there is any 60cycle hum before gutting. If it ain’t broke?