The fact that re-flowing the resistors from the top side changed something, tells me that you had another bad solder joint somewhere. Since your Percolator still isn’t working properly it makes me think that there is another bad solder joint somewhere. You may be at the point of taking the board out of the chassis again and reflowing all the joints and double checking for solder bridges (shorts).
Have you tightened the tube socket yet? If so, did you tighten the socket and re-flow the solder joints in the same step, or did you test the amp between each of those steps? I’m just wondering if it might have been fixed when you tightened the tube socket, but you didn’t notice it. If that might have been the issue or part of it then gently re-tighten the socket again…if that works it will keep you from having to remove the board from the chassis. When tightening the sockets focus on pins 3, 6, and 11 (next to R1, R6, and R11)…these are the grid pins. The “grid” is where the signal comes into the tube stage. If you have correct voltages on the other pins then it’s most likely that the signal is not making good connection to one of these pins…if it’s the tube socket at all.
I don’t know if you have one, but it really helps to get one of those solder sucker tools to remove the solder from the holes after you remove the wires. They are very helpful in putting the board back after you remove it and removing excess solder from around the pads if you have any big solder globs anywhere.
We are really close. Keep persevering!
Good luck and keep in touch.
-Brach