AM Radio reception fades in in and out

Thanks for your response, Pauly. I would tend to agree that signal strength from the transmitter may have something to do with the receiver processing the signal, but I have a feeling that one of the amplifier tubes may be malfunctioning. I reckon I'll have to go to work and try to find a shop with a vacuum tube tester in the Seattle-Tacoma area. If my recollection serves me,
I believe that the FM signal is dependent on line of sight, as FM stands for Frequency Modulation, and AM is more likely to travel a greater distance, as AM stands for Amplitude Modulation, and its signal travels in more of a wave-pattern.