Thanks everyone for all the comments thus far. They are extremely helpful in doing my research. I’m still very much in the absorbing and learning mode. All your perspectives are very helpful.
One quick response though. I can’t go and swap out one on one to find the bad tube. I tried it once and cause major repairs with my “circuit” board. Essentially the turning off and on with bad tubes fried some transistors or some other electronics. Expensive mistake.
thanks again