[Inkthinker2]

Thanks, Roslyn! I have found tube type 78 on Reverb but cannot locate type 75 yet. One site posted: Type 75 is the same as 6SQ7 and 6SQ7GT. So, I have a lot to learn about the sum of the tubes and the way certain tubes function. 

I have 25Z5 and 43 and will test them today. Next issue are the capacitors that appear to be updated in the chassis and what exactly it means to the tubes or the plug which I absolutely must upgrade for safety.