Wow, 11 years without a hiccup is an impressive feat for any old tube TV, much less a Predicta.
I would contact area radio/tv collector clubs and ask for a repairman recommendation. Here's a nationwide list of clubs:http://www.antiqueradio.com/clublist.html
Removing the chassis from a barberpole set is not terribly difficult. It only involves removing some screws and unplugging the cables for the speaker and other items. This article may give you an idea what's involved:http://antiqueradio.org/philc12.htm
I would label the ends of each cable with a tag of tape, to ensure it can be reconnected correctly. The only non-obvious cable is one that goes into the socket of the high-voltage rectifier tube. It's easier to see where that cable goes after you remove the tube. The cable simply pulls out.
Phil's Old Radioshttp://antiqueradio.org/index.html