[rghines1]

You picked a difficult set to start out. As far as distortion, I would make basic voltage checks in the audio section with emphasis on the audio output bias. Should be about -20V on the control grids of the 7C5s. Also make voltage readings on the other tubes in the radio too. Often problems can be found this way without elaborate test equipment. If basic voltage checks are good then alignment will have to be considered.

Concerns about a under-rated switch is misplaced. Tubes are usually Ok. These being locktal tubes there is concerned about pin connection issues. Rocking the tubes in the sockets can reveal a intermittent pin while listening to the radio.

http://www.nostalgiaair.org/Resources/497/M0013497.htm