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plugged in at the tv recycling day in my town. It didnt have a picture but it was picking up FM radio somehow. // the only FM station it might be picking up would be 87.7 which would be channel 6 AFAIK.
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The RCA version of this set didn't use the modern "intercarrier" TV sound method, where the sound carrier beats against the picture carrier at the video detector to yield a 4.5Mhz FM subcarrier. Back then TV IF strips were operated around 25MHz instead of 45MHz today. So this above old RCA TV set had a separate sound IF tuned to around 21Mhz. This required precise fine tuning on the front end tuner. But this also allows one to tune above channel 6 and receive FM radio stations. So that's what was probably happening with that set being able to tune FM stations. No picture probably means the horizontal output circuit is broken.