Okay I think I found it. I did make a wiring mistake!
C35 was connected to the
wrong pin of
V9 / 6BF6.
I must have been distracted, but its clearly on the wrong terminal.
Check the before/after photos below.
C35 was replaced with a MICA cap. .0051 uF @ 500v
I will remove the capacitor, check it, and reinstall (if okay) on the correct pin.
I wonder if this could have caused any harm?
Untitled by
Thomas Duncan, on Flickr
tube by
Thomas Duncan, on Flickr