Found the source of the noise. It is V18, the high voltage rectifier. The base of the tube is sparking bright light blue. Could this be a bad tube itself, or possibly a fault elsewhere causing the problem? R89 and R95 are both reading right on.
I'm sorry to be such rookie but I'm still don't quite get the ground connection for the aquadag. I've google searched the spring connections and saw a couple of examples but my set doesn't have anything like that that I can see. The only connection that I can see is a rigid wire connected to ground with a u shape around the high voltage wire. Is this supposed to be making a connection for the aquadag, or is it just to hold the high voltage lead in place? I've tried to show as much as possible of the tube in the three pictures below.
This next picture you can see the high voltage lead and the wire I mentioned with it.
