Its possible that a power tube arced.
Its also possible that a driver tube could be having some problems.
In either case, it should merely be a matter of finding the tube at fault and replacing it. You can knock on the tops of the power tubes with your knuckles- if you get a response ('sonic boom') replace the tube.
Its also possible that a driver tube could be having some problems.
In either case, it should merely be a matter of finding the tube at fault and replacing it. You can knock on the tops of the power tubes with your knuckles- if you get a response ('sonic boom') replace the tube.