To clarifiy:looking at the first photo on this page:Originally Posted by red
http://www.tubeampdoctor.com/newsdes...newsdesk_id=40
To put in a screen grid resistor, go to the eyelet for the second cap from the left, the one where the green and brown resistors are. You would solder in the end of a 470 ohm 2-5W resistor there (in addition to the two already there) and solder the other end to pin 4 on the 6V6 tube socket.