Thanks, tcarcio!
Curiously enough younger son (the one with the fiancé) and I are tomorrow heading down to a friend mine in Brookfield CT. His business is repairing audio equipment, primarily things like old Fender, Marshall and other amps for musicians, Bell Audio Lab, LLC. He's going to take a look at a 1970's vintage Marantz receiver (2280?) that my son found in the cellar of my parents' home he bought. I think it belonged to my late nephew who had lived there for a time.