[TV MAN]

Well, I was about to post the wrap up and final results on this resto and pronounce it fixed. I had moved on to restore a small Eico signal tracer, and powered up to test an unknown capacitor, and it happened. Buuuuuzzzz, crackle and that wonderful burnt smell, while at the same time my eye tube went dim - Alwright whut happened??? At first I thought R3 opened up, but when I clipped it, it checked ok. I checked some other resistors and sniffed around. It was at night, and I had my bench lights almost all off. I brought it up on the variac while I watched voltages and such, and then I saw sparks and arcing, and found this:
   
Is this a common problem on a wafer type socket? It is between pin 6 and 7 (cathode and plate) on the 6X4. There is about 700+v potential there. I separated the socket by drilling the rivet, and found carbon tracking. I don't know it this happened all at once or if this has been coming on for some time. Couple Q's.

If this happened once, this may be a problem in our humid climate, and may happen again. Would I be gaining if I used only the plate on pin 1, think that would overload the 6X4 tube? They have both plates tied together, and are using as 1/2 wave rectifier. This doesn't strike me as a high current draw circuit.  I would have an open plate tho, and that may not be good. Any thoughts?