It seems like it doesn't recognize the presence of input. You may check condition of input tube and if it's normal than I'd suggest looking arround elements on the DC and signal path for both input and splitting tubes.
It's more likely an electronic surgery problem since if tube going bad in these amps it may take some other circuit elements with it.
The fuse you're using the most tube amps use so it shouldn't be an issue.
It's more likely an electronic surgery problem since if tube going bad in these amps it may take some other circuit elements with it.
The fuse you're using the most tube amps use so it shouldn't be an issue.