I just got a used Trirec, and so far it has been amazing, it sounds perfect. But today when I started playing (at extremely loud volumes) I noticed the standby switch flashing, so I looked at the infinium lights, and as I suspected two of them were lit up. So I'm sure its just bad tubes, but I also noticed while a signal was passing through, all the lights were flickering and flashing, sometimes in sync, and sometimes in weird intervals. Is that normal? Do they always do that when there is a signal passing through? Or could the amp be defective? I've never looked at them while playing before today, and if its a problem with the amp, I'd rather just return it than pay for new valves. Thanks in advance.