CRT help

My 25 inch monitor just started to make a hissing and a popping noise. Everytime it "pops" I can see slight distortion in the picture. The popping is constant, about every 2 seconds. How hard is it to do a cap kit on a monitor board? Could it be something else that i am overlooking?

Isolation Transformer?

Hissing or cracking from the crt is most likely the high voltage at the anode cap and/or focus pins on the crt leaking and arcing.

The CRT needs to be properly discharged and the area between the anode and the aquadag cleaned using meths or iso on a dry rag.

If the +B supply voltage on the monitor is set too high this could lead to an over voltage situation also causing arcing from the anode cap, but its usually a combination of climatic effect like increase in humidity/dampness and a build up of dust around the anode.