Annoying damper heater issue update.
Last early July after it seemed to have gotten worse, I got another NOS 5V4G, last one was new when I finished the restore, now it has not acted up since.
Now it's still a socket issue and it likes the new tube more, or the old tube was having issues.

I just know it has worked OK so far, dare I put the HV cover back on and go for the long run?