I would replace the 1.5k screen grid resistors usingvthe 1/2 watt rating. Those are too big. Here is my 59 Pro, its the same as your build except a few resistors. Make sure you install the outside foil just like my original. If your tone/ coupling caps ate not marked for outside foil, you need to test and mark them. Some solder joints are not shiny, not enough heat, may cause a cold joint. You have massive 2 watt resistors in places that should be 1/2 watt. Use my amp as a guide.