Long story short, I purchased a US made SVT-CL on craigslist about a year and a half ago. The amp has been great and the greed LED bias lights on back always lit up on both sides. I noticed the other day that now only one of the green LEDs is lighting up. So during a band practice (letting it warm up properly) I tried adjusting the side that wasn't lighting up and no matter what I did I couldn't get it to illuminate. The amp does sound like it may have lost a small amount of punch, but when the tubes to out in my V4B, you can tell pretty quickly. Does this mean that matched tirad of tubes needs to be replaced on the side that is not lighting up? Or am I somehow not biasing it correctly. Has anyone else had this same issue and if so what was your fix? Again the amp doesn't sound terrible, but it might lack a tiny bit of definition.