I was king of thinking that cleaning an area disturbed the electrical
charastics of the
tube, unbalancing it, I though maybe if I cleaned all of the tube it
might
restore
that balance as it would have an even spread of surface charastics.
However eventually it does restore focus fully even with an unevenly
cleaned
tube.
Snip
I guess the only action I can take is to clean it throughly.
Snip
The area I didn't clean look black but the clean are alooks pretty OK.

Hmmm cleaned it a lot more but it's hard to get at a lot of it.
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Just how much of a "cleaning" are you doing? You do realize the black
stuff coating the outside (aquadag) is a functional part of the tube.
JC