Folks, I have a 100W Marshall Super tremolo type 1959 built in in 1970 (4 EL34s in the output). The main 4 Amp fuse pops after 1/2 minute and I noticed the EL34 plates glowing. I pulled the output tubes and read only -4VDC on the grid pin 5 of the sockets. I was looking for -35 to -45 VDC. The Fuses did not blow with the output tubes out. I disconnected the power transformer bias winding on the secondary (white and green wires) and read only 8 VAC at the output of the transformer unloaded. Should it be 100 VAC? The B+ voltage is fine at 512VDC so that part of the transformer seems OK. Thanks, Al