The crap audio quality is likely from demodulating the film optical sound track, but somebody got rid of scratches, clicks, pops, dropouts etc. so the audio has been processed/restored.
$550 in 1964 is $4,611 today so these console units are super expensive? 16 new portable models for '64 ?! Tuner with 116 gold contact rotary switch! Solid oak!
I've fixed dozens of Zenith TV's when I worked in a repair shop. They were good quality and fine to repair as you could get service manuals but the circuits always had some complicated, cute engineering that could be difficult to troubleshoot. Electronics engineering was weird back then, they did try to keep component count down but sometimes went weirdly complicated to get rid of a few parts. It didn't make sense as the sets have a zillion hand soldered parts, no PC boards yet.