more on DOC documents, etc, Hoover, Aimee
I have a Department of Commerce KFSG license file that covers 1924-1932 or so from the National Archives. There are two letters written by the DOC's 6th District Radio Inspector, J.F. Dillon, to KFSG and Aimee, 2 weeks after KFSG went on the air. Dillon says his office is daily getting complaints that KFSG is causing interference to KHJ and KFI. But, he does not threaten to take KFSG off the air. He blames the problem on inferior radios at that timer which are not selective enough to filter out strong nearby signals, while tuning for other stations in Los Angeles. That is, the problem, which happened nationwide, was that radios close to the KFSG transmitter were getting KFSG across the radio dial, when they tried tuning for other stations in L.A. Dillon suggested that KFSG cut back from 6 says a week on the air to only 3 days a week. Dillon does not say KFSG was wandering off its assigned frequency.
The Hoover Library archivist told me in 2003 that while the Hoover telegram does not seem to exist, he believes that the incident took place, based on Hoover's detailed history efforts in the past. He says Hoover first made mention of the incident in a radio speech in 1945 on the 20th anniversary of radio, and again in his 1952 memoirs. But, I see nothing on this in the 1920s decade anywhere in radio magazines of the day or newspapers. Same with DOC/FCC license files. This story then appeared in some books on radio history after 1955, but in none of the biographies on ASM, until a book on her life in 2007 by Matthew Sutton, and he used the words "Hoover claimed" that McPherson sent such a telegram.
I'll add a few more comments later.