[MrFixr55]

I am a little worried as to why you had a fireworks display in the 80. This usually occurs only when their is a short across the power supply or in the power supply, usually a shorted filter cap.

You may be able to tape the filament lead of the tube that you actually intend to use in the set after neutralization, and then neutralize the set on that tube. When the neutralization is complete, remove the tape.