I haven't heard the show, but on the Fun & Games site's "This day in AT40 history" section, there is a review of it, and one part states:
"Another act that had most of its hits in the 1960's--Neil Sedaka--was featured as host Casey Kasem pointed out that the song at #5--"Lonely Night (Angel Face)" by the Captain and Tennille--was the first Top 10 hit Neil had written in some 20 years.."
But that couldn't be true, since Neil wrote the biggest hit of 1975, "Love Will Keep Us Together"! Unless Casey said or meant written entirely by himself, since Neil did co-write that one with Howard Greenfield. Also, it's possible he meant that he wrote "Lonely Night" earlier, I dunno, again, I haven't heard the show, I'm just speculating. I know there were errors made on AT40 all the time over the years, but it seems a particularly glaring error to forget who wrote the song you just played as the biggest hit of the year a few months before that.
Yeah, there must've been some qualifier omitted (either on the show itself or in the review on this site), since Sedaka as an artist had scored two #1 hits in 1975 with songs he cowrote with Phil Cody ("Laughter In The Rain" and "Bad Blood").