So this bass amp snapped a fuse, but powered up after re-fusing (lol) and is now behaving perfectly fine, for now. But that tube in the middle has a red glow and not coming from the heater/cathode, and struck me as odd. Is this normal? Granted, it's a Chinese among the Tung-Sols. Also, it heats up like the others after 10 mins of playing, so I'm pretty sure it's working. Tia.