This article explains how to test the filament in a tube for continuity:
http://antiqueradio.org/FirstStepsInRestoration.htm
That's a simple dud/not-dud test, but that's the info you need to get the restoration started. To begin, I wouldn't replace tubes unless they're obvious duds. The others will likely work well enough to get the TV basically working, and then you can worry about smaller issues.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html