if you have an older crt,try removing the housing from the main set w all the wires & adjustable pots (= potentiometers),lightly shopvac as much dust as you can reach ( power off meanwhile),use a hand mirror after spraying a bit of non oil based tuner cleaner into each pot receptacle,,twist each one,,might be a couple dozen you can adjust,back & forth back n forth.
and some pots are offset allen type hex metal twist thingies at the side of the set,,some of these you can twist by fingers,
clean the plastic housing too..wipe with windex type cleaner.
turn the set on,,pic might be scrambled,go through each pot you cleaned,twist all of them checking the mirror for the effect,,also the spin color slot shaped adjusters at the skinny base of the glass tube.
tinker until you get nice tones & colors,,off a good quality dvd put on freeze frame,crackling sometimes is because of static electricity that periodically discharges,,grounding the chassis might stop this.