A few days ago I picked up a subwoofer and was hooking it up. I accidentally connected live line level outputs to the dynacos and it made a loud thump. At the same time that this was happening the smart switch that use to turn the Dynacos on and off had a server failure and the amps power cycled a lot quickly while I tried to figure out what was going on. Anyhow, one MKIII blew a fuse but I don't know if it was due to the power cycling, the clumsy sub hookup or something else. When I tried a new fuse it was OK for a few seconds then there was an arc in the rectifier tube and it blew its fuse. I am assuming that the rectifier tube was damaged either due to the power cycling issue (hot restarts) or the line level thump. I ordered a new JJ GZ34 / 5AR4 Vacuum Tube rectifier and some fuses 3a at 320 volts. Am I following the right course? Did I get the right fuse? Is the damage probably limited? I know pretty much noting about electronics. The board is original but was recapped and was running fine. Your help is appreciated.