[old_tv_nut]

I wonder if this was one of the chassis I worked on at Motorola, doing arc tests. There was a failure mode where a CRT arc to G1 would couple through the vertical retrace blanking cap, through the vertical output transformer, into B+, into the audio output, and then kill the audio driver transistor. First fix was to put a small choke coil in the audio output base lead, I think. Final fix was to change the audio driver transistor to a more robust part.

I can remember the feel of those small front knobs with the square hole.