Working on my CTC9

[Unimatic1140]

Hey Guys, happy holidays to everyone in Audio Karma! I've starting working on restoration of my CTC9 and I've gone from nothing but a loud buzz to a full color picture by replacing all the tubes and all the electrolytics as well as a few black beauties. At first the picture didn't have enough height, but after I found the hidden height control I was able to bring the vertical sweep all the way from top to bottom. I do need to go and recap the vertical board and I'm sure I'll find other problems too. My most perplexing problem right now is that after the set is on for about five minutes I start to hear a static sound coming from inside the high voltage cage. I checked the flyback for a pinhole opening where it might be leaking HV but the tire looks like its in great shape, with no burned areas. I tried coating the entire inside walls of the metal cage with several coats of aerosol corona dope and still I have this problem. I have been running the chassis outside of the cabinet with the lights off and I cannot see any signs of arcing, but even with the cage door open its not wide enough for me to see the Flyback so I don't know exactly where the arcing is coming from. Is it safe to power up the chassis with the HV cage removed (of course without touching anything near there)? Might the sound be coming from deep inside the flyback and its on its last leg? Any suggestions you guys might have about what to check will be very appreciated.