Here is a picture when it was being rebuilt:
http://n2dts.smugmug.com/Ham-radio/i-QJBq4hRThat cap is a 2000 volt job.
I did some more tests today, plugging in my ebay tubes one at a time and testing the plate current and power output, and then marking them.
I then put the 2 best ones in and ran the power up and arced the new cap, melted one plate down to slag.
They sure don't make caps like they used to!
I need a still higher volt cap if I want to run the voltage up higher.
I have a bunch of good new 4x150's though.