snip




PS: I did clean the inside and I reckon picture looks a bit
sharper. But maybe I am completely deluding myself! Or maybe I
leant on one of the sharpness controls while I was cleaning!


At the voltages that can be running around in the back of a crt,
cleaning out accumulated "crud" is a damn good idea, since, as you say,
some of it may well be (semi)conductive.

Even if it's inert, it'll have a negative impact 'cause it's acting as a
blanket, keeping components hotter than they would be if running in
"free air" conditions.

Good response! Keep hands away though! Make sure to use a long
handled feather duster as well as compressed air.

One minor worry with compressed air if it comes from a compressor (as
opposed to a compressed air can) is condensation in the air hose, the water
droplets can be forced under components where they take a while to dry out!
If the air line doesn't have a condensation filter - blast it out for a few
seconds before pointing it inside the equipment.