I think your ESX symptoms are caused by the tube. If you replace the vacuum tube, it is likely to be cured. No sound is produced when the vacuum tube is completely damaged. If the vacuum tube on one side is dead, it can be explained as the reason why stereo output is not possible. If the remaining tube was damaged, it would be excessive distortion. This is a phenomenon that happens to everyone due to deterioration over time. This can also happen with impact damage. When you hear your story, there is no denying the possibility of other damage. But before you go out to repair expensive manufacturers, it's better to try cheap ways you can do it yourself.