ID Question

[ekimetsok]

Could be engraved on the tube base, but more than likely, they're printed on the tube itself. If the tubes are particularly dirty, take care because those numbers rub off very easilly. There's also a chance there's a tube diagram inside the cabinet, or perhaps the tube types are handwritten on the chassis or stamped into the tube sockets. Proceed cautiously.

Hey, if this was easy, it wouldn't be any fun at all.