Joe,

You will need to determine what is arcing. Did it look like it could be coming from the high voltage cage (the box with the 3A2s and 3A3 in it)? If it is, see if you can remove the cover before powering it up just for a few seconds to see what's going on. Pay close attention to the flyback transformer (inside the cage). Also watch the tubes in the cage, plus the damper tube & horizontal output tube.

ATTN Steve McVoy: you are familiar with this chassis. Any suggestions?