Looks as if Frankie retired at 56 or so in '84. He may have been tired, may have been too much pain and hassle. He spent a lot of time it seems with Lionel Hampton. That may be a reason too!
Dunlop on his time with Hampton:
"Playing with Monk was the greatest challenge of my melodic playing. For power, my greatest challenge was Maynard. For stamina, my greatest challenge was with Lionel Hampton's big band. Just let him stomp off "Flyin' Home" and that song will be going for 30 minutes. If I wasn't in 100% physical shape, I'd be biting the dust right now. I was with Hampton for seven years. There have been quite a few drummers that Hamp worked to death. Wilbur Hogan and George Jenkins come to mind [...] In Hamp's band, the drummer is a workhorse. In any Lionel Hampton set, you can look for five tunes: "Sweet Georgia Brown," "Basin Street," "Flyin' Home," "Hamp's Boogie Woogie," and "In The Mood." Those are five songs that you're going to do every night, come rain or come shine. And those are the back breakers."