So today I took the back grille off my Valve Junior and started testing how easy it would be to change the tubes that way... I took out the tubes and put them in again. But then, the amp wouldn't produce any signal! The tubes were glowing healthily, orange at the tip and violet in the middle, neither were they overheating, I suppose... So what could be the problem? Are the tubes maybe broken? Interrupted circuit? Input/Output damage? Help if you can
You really should wait a while, like a day, before you take the tubes out to let the filter capacitors lose their charge. Also make sure you put them back in the right spot