Tonight my amp went a bit bizerk. Mesa four channel amp decided to auto switch channels 3&4, but on the amp both channels were lit. The foot switch took a moment to get things right. I unplugged the foot switch, plugged back in and seems to be working. I check the back and this picture is what I see. Not all tubes are looking the same. I did buy this used a year ago so I am thinking it might be time for a new set of tube? Thoughts?